Psu advice

[tm211]

I've got a Dell Optiplex gx620 (desktop chassis).
I'd like to upgrade my graphics card from an ati x600) and after a bit of research into lo pro cards have decided on the nvidia 9500gt.
However i'm pretty sure this will require a psu upgrade too but due to the small form of my pc this is proving difficult. any advice or recommendations would appreciated.
Thanks.

 

[evongugg]

Please tell us how many amps you have on the 12v rails and the wattage of your power supply.
Look at the label inside the computer.
Please list all your hardware, so we can calculate it.