Nvidia Geforce 7300video card replacement?

So originally I had in my dimension e520 the video card nvidia Geforce 7300 (idk what edition it was) but it burned out apparently and now I'm being forced to use the Intel family G965 express chipset family that was also on the computer.

I was looking around newegg, amazon, etc but almost all video cards exceed my wattage level by 2 times   and there's a bunch of different versions for PCI Express x16

Could anybody be kind enough to direct me to a video card that is similar to the nvidia 7300 and dosen't require me to upgrade my power supply, because before I used to be able to run low graphics required games ,like left 4 dead 2 and crossfire, and surf the web fine.



My computer specs are this (got it from the manual)
Wattage 305 W
Maximum heat dissipation 560.5 BTU/hr
Voltage
90 to 135 V and 180 to 265 V at 50/60 Hz

2X1gb ram

PCI Express
connector one x16
connector size 164 pins
connector data width (maximum) 16 PCI Express lanes