Well im no expert on this but I will see if i can help.

I had the same problem with a power supply I had. 350 watts is pretty low for running any kind of game. It may be that the powersupply is dying out, which is then causing your videocard to not work properly. I had a 650W powersupply and when I would try to run a game, the pc would restart (which just may be due to the beast of a video card i have).

The eventual restart of your pc sounds like overheating. Make sure there are no wires or anything interefering with fans...and if you need to, or want to put in the effort, install a better cpu cooler and another fan or so for better circulation.

Are the black dots pixelated? Like small blocks of black. This may be due to your video card aging and producing artifacts. This may be due to the powersupply not being enough for the card, the card being old, or the game being too demanding for your card.

Sorry if i stated the obvious, but thats all I can think of.

its still practically brand new, the first 2 months have been spotless with no problems, but now this crap. granted the restarts happened even with the original 450 watt power supply  a few weeks before its final death.

since the original set up used a 450 watt psu, now with a 350 psu and I also happend to upgrade my ram from 1 to 3 gigs. would a 500 watt be sufficient or might I need to go up to 550? taking into account that my next upgrade will be the video cards since i desperately need it, nvidia 6600gt isn't keeping up anymore and I never get to play games even in medium quality, im loosing out to prettyness here since i haven't had the luxery of beefing up my gfx to basically anything released outside of 2005, sure i can run medium settings but then i suffer in FPS of about 10 or lower. tf2 chokes even on the lowest settings in wide open spaces with lots of players on the screen. i got an effing 1680x1050 screen that im always forced to play in 1360x768 or lower.

p.s. now my sound is fucking up, it cracks and stops any video being currently played be it from my HD or on the net. this usually only happens when I got firefox opened...... wtf seriously? never had so many problems with my PC at the same damn time.

Honestly, a 6600 runs on something called an AGP bus. You can't put a new (8800 or newer) graphics card on that machine. And if you do, you'll need a new power supply and probably a new motherboard+CPU. Replacing all that crap would be as expensive and less powerful then just throwing the whole machine out the window and buying a new one. I'm kind of in the same position with my computer. This processor is from 2003 and it can't take much more abuse. My advice: when Windows 7 comes out, buy a new computer. Pull the life support on your current rig.

I said fuck it and got a 650 watt psu, ive yet to run any games to see if those black spots are gone yet. thx folks

*edit* well things still running fubar, even with a 650 watt psu my comp still has the black blocks and restart still happens if i dont use the the external cheapo fan. my last best guess would be it would have to be the video card itself. I accidentally got the wrong one today, a BFG nVidia Ge-Force 9400 unfortunately its a single card thats not SLi compatible so im goin back to the store for about the 4th time.

granted my rig is about 5 years old now it can support newer video cards, my older vc isn't agp its a pci-e.

it seems the restarts was caused by the video cards, they aged and are now officially in their resting place. Im finally now up to using a BFG Ge-Force 9500 gt, I ran a test today in TF2 and I finally have some gfx power to spare. My FPS ran up to 75 on the source engine stress test. HUGE improvement from my now dead 55 fps. since replacing my video cards the restarts have stopped and the black dots are no longer an issue.