It still confuses me after having it explained to me several times: How does dual-wielding work in D&D 3.5e and what is the point of building a character around it?
When you dual-wield in 3.5e, you get one extra attack with the weapon you wield in your off-hand. But, if you attack with both weapons, all of your attack rolls in the round take a penalty. The penalty varies depending on if you have the Two-Weapon Fighting feat and the size of your off-hand weapon. The penalties are given in a chart on page 160 of the Player's Handbook. The feats Improved Two Weapon Fighting and Greater Two-Weapon Fighting give you additional extra attacks with your off-hand weapon, but those additional attacks also carry an additional penalty.
Dual wielding gives you more attacks in a round, but denies you use of a shield, so it's essentially choosing offense over defense. It favors characters who like to deal a lot of damage really quickly and then back out to avoid a counterattack.
I don't know if that's useful at all, but that's essentially how dual wielding works. Hope it helps.