Okay here's my big question. After working with 7 beta and doing the work arounds and getting all of your stuff insatlled and working properly One would hope that MS will allow you to upgrade the beta to the retail. Man I don't want to go through all that again.
The bset way round this problem is to keep your current (pre W7) OS also up to date -- apply updates, install the same software on the old OS as W7 etc etc. - This is for VISTA installations. For XP the only way to upgrade is first Via Vista and then to W7.
Now if you don't want to keep a separate machine for the old OS -- either "Image" it or "Dual Boot".
My preference is for "Imaging" - if you Dual Boot --especially with a Beta test OS and something goes wrong then you are Royally hosed up as it's 2 OS'es that'll need fixing.
It only takes around 30 Mins to restore a full (with loads of Large apps such as Office 2007, Photoshop etc etc) VISTA ultimate X-64 35Gb installation so smaller installations will take a lot less time.
So when W7 comes out for real you can just "upgrade" your previous OS.
In some cases Upgrade is a viable option -- however for others it could be better to just bite the bullet and re-install.
I'm dual booting with Xp and 7 so I have no recourse except a clean install. It's not that I mind so much as by the time 7 is released I will have forgotten how I got some of my stuff to work. I wonder if I was to ghost 7 and put it on my external drive if I could re-install it that way? I guess all it would do would be to restore the Beta and who wants that?