Depends on the games and OS u running. More RAM will be driven most effectively by W2K, I think. But sure, no matter your OS, your PC will run faster if you double the RAM. But I think, the weakest link in your system is the videocard, especially if you use higher resolutions and 32-bit colour mode.
i'm running windows ME(yeah i know it sux)
and yes i know...
my video card really sux
and i'm thinking of upgrading it to geforce 4 ti 4600 as soon as NV30 comes out!
BTW thanx guys
gotta persuade my dad o get addiotional ram!