64 bit vista is as easy to install (very easy) as another version of windows.
use boot camp to partition your disk, use whatever you think is necessary. my fully installed vista OS takes about 20 gb, so keep that in mind.
after partitioning in boot camp, say "quit and install later" then start your computer with the windows dvd inserted... hold option/C and start from disk.
format the partition (the one that is as big as you chose) as NTFS and you're good to go!
i highly recommend downloading macFUSE and NTFS-3G so you can write to your NTFS partition from inside OS X. really makes the two installations seamless. and vmware fusion is pretty amazing too
i am regularly using windows these days... don't listen to the fanboys who froth and scream "OMGZ VISTA SUXXX!!1" all day... it really is a nice OS, if not as well thought-out as OS X. there are still many, many, MANY things that you can do in windows that OS X just can't do. at all.
as for drivers, the apple cd will be good enough. it will install apple software update (as long as you let it) and that will take care of important driver updates. i recommend against downloading drivers through windows update... the only ones you want to upgrade outside of apple's software update are the video drivers. go to
www.laptopvideo2go.com and get whatever the latest forceware is. really makes an improvement in games.
and to whomever said there are "4 hours" of updating and restarting, that's simply not true. i did the entire process last week, and there 1 restart after partitioning with boot camp, 1 restart after the vista dvd copies installation files to the disk, and a third restart when installation is complete.
then one more after installing ALL the windows updates, which it DOES do in a single run. really not too bad at all, and the entire process took under two hours (one hr for installation, another hr for downloading and installation of updates. quite reasonable).
the only thing you need to make sure is that you're around the computer when it does its auto restart during the installation... you need to boot into the windows partition, or it will just automatically enter OS X and not finish installing until you go there and let it.