OEM is fine. I would never buy a retail OS (except OSX its cheap anyway). Unless your the kind of person who needs tech support from some moron on a phone (forums are better).
everything looks fine, only thing is your links aren't working (for me anyway). But I have looked at most of those components myself when I built my own just a few days ago and look as everything works together. Only thing is, do you want to do SLI? if not you could go with a cheaper Mobo.
No comment on the sanity or lack thereof, but I would avoid the 7xx series motherboards like the plague as well. Until or unless Nvidia figures out how to cure the problems, they are just too unreliable for my taste.
Welp -- how about these adjustments...
OCZ Reaper (2 x 2GB) DDR2 1066
Any advantage to pairing a gigabyte mobo with a gigabyte gpu?
Do ya'll think I need to upgrade the fam and anti-heat slime or is stock good enough?