Graphics card's role in booting up computer

[tokyotech]

I have a 3 year old nVidia GeForce 8800GT 512 MB at stock frequencies. I upgraded to the newest nVidia drivers last month. Last week, weird patterns would appear on the screen while doing 2D stuff and the computer would freeze. Multicolored triangles would appear when playing 3D games and also freeze the computer. On bootup, I noticed a uniform grain over my motherboard's intro graphic. Also when the big white text on black (I think this is DOS) is printing out what is booting up, white squares and foreign characters are plastered all over the usual text. During this bootup phase, what is the graphic card's role? Has the graphics driver even loaded before Windows starts? I need to know to decide weather it's a hardware or software failure.

 

[DXRick]

Can you boot into safe mode? It sounds like a hardware failure.

 

[tokyotech]

Yes, I can boot into safe mode (if I can even read the mangled safe mode prompt). Safe mode is quite stable, but there's grainy patterns plastered everywhere.

 

[majin ssj eric]

Sounds like your video card is going bad....

 

[tokyotech]

Is it likely that I only need to replace my graphics card and no other component is damaged?