video card

I need a new video card, and i need some suggestions.

Specs:
Dell Dimension 9150
Pentium D CPU 2.80GHz
2.50 GB RAM
Dell 24in monitor
Phillips 42in hdtv


I previously had a GeForce 7900GT onboard which i hooked up to my 24 in dell monitor and philips 42 in lcd hdtv and was working fine for a lil bit, but I started to get miscellaneous pixels all over my screens. Most likely due to busting up my RAM or whatever I dunno, I am not that really good with computers. I switched to my older video card to make sure it was the video card which it was because there are no more pixels.

I am not a big video game person, I am more of an entertainment person. I just want to be able to watch my videos from my computer onto my monitor or hdtv. I have a dvi to hdmi wire running. As for sound, I have that taken care of with an optical wire running to my home theater receiver. Does anyone have any suggestions? I think my 7900 GT had 256 ram, would u suggest going up to 1gb? Will my power supply play a factor in this? I just dont want the same thing to happen again with all the pixels and stuff. Thanks in advance.

shon