Thanks for the link UB... but I'd like to sit tight and wait til release to see "real world" upgrade issues / successes.
I always clean-install my OS, it gives me a chance to rid my system of too many installed useless programs I amass over the years!
If someone is hell-bent on actually upgrading the PC, my advice would be to back up everything as if they were reformatting the disk, try the upgrade first, and THOROUGHLY test their programs to see if everything still works now!
I actually upgraded someone's limping Windows ME system to XP once (I would have been reinstalling anyway, so wanted to see if it worked!).
To my surprise, it did work, marvellously, and that person is still using the upgraded system today, it's as solid as a rock, and now about 4 years on!! So upgrades CAN work, it's just that the chance of ridding your system of crud is too good an opportunity to miss for most techies