Last weekend I spun up a dual boot environment with Ubuntu and Vista. It worked find even with BitLocker enabled TPM+PIN. I used Grub as the boot loader but here are instructions for using Vista's boot loader.
Link to Port 25 : Using Vista's Boot Manager to Boot Linux and Dual Booting with BitLocker Protection with TPM Support
BTW, I found to remove Grub and put back the Vista boot menu I had to boot the Vista DVD and run bootrec. I tried all four options but /Fixboot appear to be the one that fixed the MBR.
(edit 7/30/2007: I've performed this many, many times since March and it looks like to fully restore the boot loader you need to run bootrec with both /fixmbr and /fixboot. Has worked every time.)