go to a local computer store, or cyberpower pc, or something of the sort if you want someone to put one together for you then, eh?
otherwise, even a 500w quality psu would power whatever your trying to run as long as your not sticking in a gtx 280 or something...
barebones is your choice, I personally would never buy one, just buy my parts seperately. Barebones don't come assembled, they just come w/ all the parts.
even if you went i7, guarantee in 2 years time you'll want to upgrade to "keep up with the times"...the wont last too long in the world of technology.
you'll be shelving out close to $1,000 for the memory, processor, and mobo to run the i7 as well.
also the 630i mobo doesn't have pci-e 2.0 so you'd be losing quite a bit of performance from any pci-e 2.0 graphics card...like your 8800GTX from what I call the 8 series is pci-e 2.0, the 8800gt is what im recalling from, and if it's a GTX i'd believe it'd be 2.0 as well but it may not be...
and with the looks of the case, you may not ever be able to sit a GTX 260, or 9800GTX+ in there when you decide to upgrade that 8800...not a lot of space in the case :x