Personally I wouldn't use a beta OS on a primary machine
If you have a spare machine, or even just a spare drive (they're so cheap now) you can swap in, I'd suggest you give it a shot. That way you have some idea how it works, and whether or not you like it, before it's out.
I think the whole "wait for the 1st or 2nd SP" thing is way overblown. I might use that caution when deploying in a business environment, but for home use it doesn't make sense to me. If there's some new app/release that has features I want, I'll wait till it's out long enough that I can read a few reviews on it, and if it sounds good I pick it up. I wouldn't call myself a cowboy, although I do love old Clint Eastwood westerns. I just know if something "breaks" because of some software on my machine, I can fix it easily enough. Or I play with it in a sandbox where it can't do any damage anyway.
For an OS, I would suggest taking note of the important apps you use (anti-virus, PS, etc), make a note of your hardware, then after Vista is out, search around to see if anybody is running into any issues. I remember when XP came out, there were lots of little driver problems, and some apps just wouldn't run. But most of those problems were resolved within a period of weeks/months (way before any SP was released).
Good luck,
Kevin
