Upgrading to ATi x1650 Pro?

I have a Dell Dimension 4600 with 2.8Ghz Pentium 4, 1.5GB of memory, and nvidia fx5200 video card. I want to upgrade to either the ATi x1650 Pro or the nvidia 7600gs. My question is that I know that my current power supply runs the fx5200, but will it work with either of the cards I'm looking at? Note: my computer uses AGP.