I went ahead and pre-ordered my upgrades for Windows 7 today. I opted to get the "family pack" upgrade - three licenses to upgrade to Windows 7 Home Premium for $150. At $50/license, I couldn't say no. I'll start the upgrade with my Media Center front ends and do our primary laptop last, just so if anything happens to go south I'll always have a working computer to go searching for help/fixes. Not that I anticipate anything going wrong, just... well, things that should be easy never are for me. I always seem to find that one edge case.
Anyway, if you're looking to upgrade more than one computer, that three-pack might be the way to go. Considering a single upgrade license for Windows 7 Home Premium is $120, three licenses for $150 is a steal.