I use the upgrade Disks to do clean installs, so no you wouldn't have to reinstall vista just to reinstall 7 if you ever had to.
Look into getting an OEM copy instead; if you're in the US that is.
32-bit
http://www.newegg.com/Product/Product.aspx?Item=N82E16832116756
64-bit
http://www.newegg.com/Product/Product.aspx?Item=N82E16832116758
Yes, I am indeed in the USA, and I really thank you for this link. That translates into a bit of savings for me, over what I had recently found. I am sure to order this, and only hope that the XP program compatibility issue is all that it is cracked up to be - with this pro version of Windows7.
All it really is is a different version of Microsoft virtual PC (it allows for easier file transfers between windows 7 and the xp compatibility mode mostly) and an already installed copy of XP.
I thought the XP program compatibility was pretty worthless anyway. I only tried a few non compatible XP programs (Video Editing), but they didn't work.
How are you hampered by your machine being 64-bit? Pretty much every machine is 64-bit these days. You can still install 32-bit software and hardware into it.