That video card will work with your motherboard. You might want to check and see if your power supply is able to handle the new video card. The Dell power supplies are not know for being powerful.
According to who?
metsownme, You have one pciex1 slot and a pciex16 slot
Your psu is fine for the 8800GT, 350W @ 28amps. Your cpu might be an issue, if anything.
My 305w Dell had 22amps but I upgraded for the 8800GT.