Hmmmm . . . sounds familiar, this past weekend in fact.
I had the same problem with a desktop PC of 5 year vintage. XP Pro Media Centre OS.
Copied everything to DVD, including the B&O Beoplayer, and music, photo, and video files for the Beoport. Changed the memory and HD which was relatively inexpensive. The reinstall took 37 minutes exactly, including the AVG reload.
But the Media Centre reload ( now at version 11 ) lost some DVD capability, which was corrected with video decoder upgrade downloads, and a newer download of Roxio Sonic Cineplayer. All of this took most of the weekend.
Looking back, I think I would add a 500 GB external HD for the files I copied onto DVD. Less cost and just a pull of the Firewire or USB to detach from the PC. I'm looking into adding the Porsche LaCie HD as we speak.
Comparing the Media Centre, MediaPlayer, and B&O Beoplayer today, I'll stick with B &O for general listening, as it just keeps on playing, album after album.