Hey i have the basic set up you're suggesting... Basically, Nope the GRUB boot loader will have no negative interactions with Vista Boot Pro (as long as you set it up correctly)...
I think i used the instructions on the 4th page of this article(
http://apcmag.com/how_to_dualboot_vi...lled_first.htm ) to help set up the bootloader... But basically in my system when choosing Vista from the grub menu the Vista boot loader would load (and either give me the option of loading different OSes or just load vista(if only one entry is in the Vista Boot Loader)...
Cheers,
Jamey
P.s. that article may not be what you're looking for(it may be for the vista bootloader) but the process is simple (and depending on what distro you're installing there may be an entry for Vista pre-installed [when you install linux])...