i have mine setup with
1.5 gig active primary partition
then logical 25gig xp32 /vista64 50 gig/vista32 50 gig/ Windows 7 50gig /2x 50 gig spare for new installs
the one thing i found vista installs on this config no problems but 7 would only install if i started the install from with in one of the existing operating systems
i do this config as its easier to recover if something goes wrong with one of the operating systems or active boot partition
cheers brad