Upgrading an HPE-502c

Hi I was wondering if it's possible to chance the power supply and the gpu for my hpe-502.

http://h20000.www2.hp.com/bizsupport/TechSupport/Docume...

I'm planning to install a gigabyte 7950 and changing the power supply to a corsair 650w. Will my gpu fit in the case and work with the motherboard? I'm also planning to still use the 7950 in the future, how long will it last me? Should I decide on another gpu instead?

Thanks.