Thanks everyone for the advice.
I bought an Asus HD 4670 from http://www.ewiz.com/detail.php?name=AS-4670_51
for $62 including a rebate, cashback and shipping.
Can't wait to test it out!
I bought an Inspiron 530 recently. I ordered with an integrated Intel GMA 3100. When I called Dell tech support and asked about a 512 MB card, I was told that I may have to upgrade the power supply. He suggested me to buy Nvidia 7200 GS, but I wanted a better performing card. I prefer Nvidia cards because of better Linux support.
Can sungkum or somebody suggest to me better performing cards(with out upgrading the power supply)? Thank you.