I want a fighter/sorcerer class that won't bog down my team-mates. Any ideas what to do?
I'd like him to be able to have his spells as his main line of attack/defence, but [a certain amount of physical prowess is also wanted] in doing a tricky job such as a strength test, or making it so that he will be able to pass a certain check in dexterity. If his spells fail then I would like him to be able to kill using weapons with some ease.
What you want to play is nicknamed a "Gish." There are a number of gishy resources available for 3.5 here and here.
A gish uses his spells to enhance his battle prowess and combat capability, while being a melee character at heart. In exchange for this versatility, they tend to be somewhat... fragile, though with the right spell selection, this is not the case.
Quoth the second link:
Gish is the term used for any fighter/mage build where the character's focus in both spellcasting and martial combat is at least somewhat equal and where both aspects of the character are viable. Spellcasting and Manifesting (for psionics) can usually be used interchangeably.
If you're playing pathfinder, this answer is obsolete.
The trick with "gish" is to make sure you can both effectively cast spells and effectively fight without sacrificing too much of either side. This requires a certain amount of hoop jumping. I disrecommend using a character builder for 3.5 characters as it's worth getting your hands dirty by understanding every aspect of the mechanics. I made the mistake of starting my 3.5 career off with a character builder and it delayed my understanding of the system considerably.
If you're interested in something "simple" I recommend the Duskblade. They are described as "Gish in a can" and as a class that can use a sword and spells by default... they are. On the other hand, they're not as effective as many many builds.
For race, I recommend human or Illumian (depending on what books you have available.) A human's bonus feat will be handy, and the "Aeshkrau" from an Illumian is designed for a gish.
On the other hand, this default build from the first link is simple and has quite a lot to recommend it:
Dwarven Tank 28 point buy str 12 dex 12 con 16 int 8 wis 8 char 14
fighter 4/ sorcerer 2/ abjurant champion 5 / runesmith 1/ eldritch knight 8 BAB -18 CL 15
suggested feats - Arcane strike,exotic armor pro - Dwarven Battleplate , Armor Specialization and weapon spec with a two handed axe or hammer ( for stereo typical dwarven feel ).
Pro - good HD for most levels, simpole build that doesnt have a lot of dipping, natuarly high base attack bonus so does well in anti magic areas. sorcerer gives lots of spells for arcane strike without a huge casting score, or rings of wizardry to gain extra spells per day. no arcane spell failure in
Cons- lower Caster level only get access to 7th level spells pre epic. ( not a huge problem but not always desirable) and small lack of spells known due to sorcerer base. i like this for a first attempt at playing a gish it is playable from levels 1 and on as well as letting oyu learn the basic tatics of a gish in combat. also with the high starting con you can tank and be front line melee at all times. when you add in buff spells you can get more HP than the tarrasque or an ancient dragon easily by 20th level.
To unpack the above description, the essence of it is the "arcane strike" which allows you to channel spell levels into direct damage. This allows you to focus more on utility spells and a broad spell selection (which is tricky to pull off with a sorcerer). For details on what spells to choose, I recommend asking a new question if you decide to go with this build.
If you want to retain the fighter/sorcerer and not use another class (such as the duskblade, or hexblade) you want to focus on spells with high damage, and is not subject to spell resistance or a save throw. As you plan to use the magic aspect as your main damage, I would suggest orb spells (e.g.lesser orb of acid) that you can find in the Complete Arcane supplement. This will allow you to have good damaging spells without the need for high levels as sorcerer.
As for the fighting aspect, you can focus on feats for a single weapon, which will allow you to make up for the loss of base attack bonus due to multi-classing. It is a simple matter of balancing with feats and spells to ensure you get the results you want.
Otherwise, I would look into some prestige classes, or other classes that all ready combine similar multi-class abilities. Hexblade with curses and spells, Duskblade with spells and sword, or try for prestige classes such as Abjurant Champion, Green Star Adept, etc. that focus on combining physical combat with magic. Hope this helps.
It might be possible to make a straight sorcerer who simulates a fighter with buffs, like bull's strength and false life. I got the idea from playing an abyssal bloodline Pathfinder sorcerer who has natural weapon claws to fight with and gets bonus buffing spells known. Then you take other damage-increasing sorcerer stuff like Arcane Strike and Chill Touch, which lets you deliver negative energy touch attacks along with your claw strikes.
Eldritch knight is indeed nice, but there are more and different ways to pull it off. If you are for certain taking a level of fighter, I recommend taking at least one level of spellsword from complete warrior. BAB, ignore spell failure 10% and adds caster level. I second recommendations for duskblade, but would constrain it to no more than three levels as their spells leave something to be desired. At third level, you'll get to channel spells through your melee weapon as a standard action.
From Complete Arcane, I would make these suggestions:
Acolyte of the Skin 2-4 levels. Requires fifth arcane caster and knowledge (the planes) 8. Grants +2 dex, darkvision 60' and potentially a couple of decent spell-like abilities (poison as per the spell, stunning gaze). BAB as cleric and caster level every even level. (Alignment restrict - nongood)
Blood Magus 1 level. Requires great fortitude and toughness (both fighter bonus feats), concentration 4 and fifth level caster, as well as being returned from the dead. You automatically stabilize! +1 caster, no BAB though :(. (Alignment restrict - not lawful good)
Green Star Adept Already mentioned.. At least four levels. Requires BAB 4, and a bunch of other small requirements but only arcane caster one. Your class level for spells improves ever even level, but your caster level includes every level in the class. Slam attack, fortification, I can see why others recommended it though I've not used it myself.
Mindbender 1 level. Requires some skills at four ranks, fifth level caster and ability to use charm person or an equivalent. +1 caster level and telepathy! Useful both in and out of combat. (Alignment restrict - nongood)
Personally I wouldn't use so much eldritch knight, never have in the many fighter/mages I've run. It's a means to an end, such as when one needs better caster level. Keep your sorceror level as low as you can and don't get a familiar, get instead metamagic specialist from PHB2. Also in PHB2 is the duskblade and their wonderful enchantment "twilight," which reduces arcane spell failure by ten percent. Check out blended quartz as well, from arms and equipment (?). Of course, one can not often go wrong with mithral.
