You wouldn't gain any performance. I assume your hard drive is very old, and it slows down the system so much that any upgrades you make won't help loading times. Anyway, Xp 32-bit won't even recognize 4GB of ram, it will recognize somewhere between 3.25 to 3.5 GB. Honestly, 3GB is a good amount for XP, go for that if you can, anything more than that is a waste of money.