Pick over the list at http://www.tomshardware.com/reviews/best-graphics-card,2569.html
Now you can pick by price and watch out for notes about power supply requirements.
I'm not particularly looking to add a VGA graphics card to play high intensity graphical games. I want a decently afford-ably priced VGA card selling on eBay, that can help my system boot-up & multi-tasking work a lot faster. Can anyone explain to me the graphics cards are categorized? I don't want one to watch TV or movies, just improve overall system performance. Is it the clock speed in the card that can tell me how fast it works?