Anytime I get a new box, regardless of OS, I always take some time to "burn in" the OS a little. I would suggest slapping Vista on the new machine and get familiar with the featues, etc...
Then go ahead and toss on your productivity apps and such to see how they are working for you and finally toss on SP1 to make sure all is playing nice.
At that point, you should be good to go and can bring your stuff over without too much worry.
[Full Disclosure: While this is my "ideal" situation, my last hardware change was rather abrupt as I had to turn in my old laptop by a certain deadline so I hastily went from Vista 32 to Vista 64 utilizing the new Santa Rosa chipset, etc, etc on my Compaq 6910p. I am happy to report there have only been a few minor issues and no show stoppers]