help with graphics card upgrade

[rpgamer127]

so I've been thinking about a graphics card upgrade but i have not been able to find a card that will fit into my dell 531s and considering the power supply is only 250 watts its even harder. but recently i stumbled upon this site http://extreme.outervision.com/psucalculatorlite.jsp and it says that I'm only using about 190 watts of that excluding my current video card which is an ATI Radeon x1300 pro.

my current PC specs:
dell inspiron 531s slimline case
Intel model 0RY206 motherboard
amd athlon 64 x2 3800+ Windsor
3 GB Dual Channel 667 MHz ram
ati Radeon x1300 pro 256 MB Pci-e x16
onboard audio
cdrw/dvd combo drive

thanks in advance,
Eric D