I'm just about to put this to the test, actually - my PC crashed a couple of days ago. I'm writing this on the new one.
When you back up using the Export function, you should be able to specify where the files are backed up. I specified a folder on the hand drive and Exported my patches, then backed up that folder to CDRW. Whenever you Export again, the software remembers where the backup goes on your hard drive.
On your new computer - this is the bit I'm going to be doing shortly - you use the Import function. You need to copy your backup folder(s) onto the hard drive first, as you can only Import with the original installation disk in the drive.
Import is so quick and painless that you may not realise it's happened. The first time I did it (after reinstalling one of the Arturia programs) I didn't realise it had been done and I did it more than once. So just click to Import and then check your patch menu. You'll probably find it's happened in the blinking of an eye.
Regarding `upgrading' to a new computer, I wince every time I hear the word `upgrade' as what Microsoft call an upgrade (and Apple too for all I know) is debatable.
If you're thinking of moving from Windows XP to Vista, don't assume things will get better. I've heard various reports of problems running music software under Vista, including Arturia stuff and NI's FM8.
Of course Microsoft tend to release new versions long before they're ready, and patch things up in the following years, but that may not help and I don't expect them to even understand the issues with music software. I'm currently preparing for a long haul with XP. I bought a second XP machine for that reason (now my only one, since the first one crashed). In my view it's worth being able to keep running XP until we know for sure about Vista.
Of course I may be wrong. I've not used Vista myself, and people say all sorts of stuff on web forums. But one of the comments was from a musician who definitely knows what he's talking about. He's used computers in the studio and on stage for years, and what he doesn't know about synths isn't worth knowing. So if he says there are issues with Vista, there definitely are.
Anyway, see how you go and I'll look back at this topic and try to answer any questions. I should be doing my installation on this PC in the next few days.