I just got a copy of Windows 7 Ultimate from my good buddy at Microsoft. Is there any way I can install it without having to wipe my hard drive?

Upgrade might work. It worked for me when going from build 7060 to 7100.

I have noticed that the box has a leaflet packed in that tells you to back up all your files if you're upgrading from XP to 7. Maybe that means Vista and 7 Candidate users are covered?

I don't want to guarantee anything but going from one version of Win7 to another should be painless as it was in my case. Even my default programs were unchanged. However it's better to backup anything important first as you never know what might go tits up.

I'd recommend that you backup everything that you have, and then fresh install Windows 7. Yes, after installation it could take a little more time to install everything that you have again, but it could save you from all the potential problems that could come up when upgrading from previous Windows versions.

I have no idea how well this works yet, but I did find instructions on how to upgrade an RC to RTM.

All my friends that used the Evaluation had to do a full clean install. Time to back stuff up!

If you're using the RC then I'd recommend you do a format and fresh install. Just backup the install files for your drivers and programs and go for it. The RC was wanky and should be wiped to remove every trace of it.
If you're using the beta version then maybe upgrading your installation won't be such a bad idea.

I've had a fair bit of experience playing around with stuff like this, I did something similar with vista and it was a fiasco.
Basically my advice is to do a format and full reinstall because the only thing that an upgrade buys you is the convenience of delaying a format and full reinstall in order to fix all the issues an upgrade usually brings a month or 3 down the track

I'm getting the free upgrade option (free with copies of Vista[url=www.windows7upgradeoption.com](www.windows7upgradeoption.com)[/url]).
I'm assuming that I only have the option to upgrade, so no clean install for me. Is that going to be a bad thing? (Vista64 home premium to Win7 home premium)

At least in the past the upgrade installers let you do a clean install, you just had to insert a disc from a valid product at some point. In the case of the XP upgrade install, you told it where to install, what type etc and just before it started it asked for a 95/98/me/2k disc to prove you actually own a copy rather than just bought the upgrade because its cheaper