Just a quick hardware/software question?

I currently have a voodoo 3 grafix card, and a P3 45o mhz
after i installed win xp Enterprise edition it loads up to the login screen, but the problem that i am having is that my monitor loses sync with the pc (cant see the screen)....I restart it, and see win xp loading but then i get a yellow light on the monitor at the login where i cant see anything...

Any help would be greatly appreciated in this matter,,,,,,thanks

m0lluck