Now, here's a problem you don't get to see around very often

I've been kind of bored lately, and decided to put together a gaming rig, system consisted of old school hardware, mostly 2000-2001.
To cut it short, the game DOES load, and it's mostly playable, with occasional lag and/or slower texture loading, except for the flickering text & HUD problem. Doesn't seem to affect radar though, only HUD and subtitles, along with mission instructions text and pop-up notifications in the top-left corner.
So, I'm curious, is there a way to resolve that problem? (Or is it because of hardware limitations?) I tried to play GTA3, and it seems to be working just the same, slower but stable with absolutely no flickering at all.
My system specs are:
AMD Duron 750MHz
128Mb SD RAM
Matrox Millenium G450 DualHead 32Mb AGP 4x
Maxtor 30Gb Hard Drive
Pioneer DVD-ROM Drive
Windows XP SP2 (perhaps I should try with Win ME?)