Yea Hiper and Hiper Power are the same, decent PSUs, look nice too
however if you can get that PCP+C one, do so. Good question about the power requirements for 7800GS but i would say the same still applies, especially with dual core and overclocking. It would also allow you to add extra hard drives / water cooling / fans upon fans etc.
I wouldnt worry about breaking anything, just do it one step at a time and take your time about it

I wouldnt worry about breaking anything, just do it one step at a time and take your time about it