Flicking Screens !!! please read and please help!

Well… i recently brought a tnt2 32 meg m64 and well… when i try to play… my screen flickers…in direct 3d… and open gl it goes fuzzy everywhere and i have to reboot these games have been
Quake 3
Half Life
Quake 2
but only like on the net (i think) or multiplayer PLEASE Help GUYS!!

Forgot to add a few bits as i noticed
Win 98 P3 450 128 meg of ram

hmm yah