I only have a duron 800 and TNT2, and i have no problems with those sorts of tasks.
Sounds like a problem with your setup. XP is memory intensive, and 160 megs is not really enough.
Use Task Manager to see how much available ram is left when you boot to the desktop.
More importantly, how big is the swapfile. This will tell you if you need more mem.
Regarding the FPS issue, are you using the latest drivers frrom Nvidia? (not the built in drivers) The latest ones are Microsoft signed.
Good Luck

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