Hmm. I guess besides my laptop I have never bought a pre-made PC at a big name retail store. The one I currently run I got as a local computer store was going out of business and it was a good deal at the time (about a year ago now)
I picked up my pre-built PC (it was made by the guy there, so I guess somewhat pre-built) which has a i7, ATI 5570, 2TB HD with hot-slots in the case, BR-Drive, DVD-drive, 8GB DDR3 for about $750.
For the price at the time its pretty good, everything works well and what not, but then again, this was not a big chain store either, this guy most likely knew what he was doing.