I have only ever installed dual-boot systems on the same drive (separate partitions) but it should not matter if all the drives are connected provided you install to the correct drive and not overwrite your original drive.
A how to tutorial can be found here:-
http://apcmag.com/how_to_dual_boot_windows_vista_and_windows_7_vista_installed_first.htmAs for choosing which OS to boot into, see using "EasyBCD" in the link below and the last but one post.
http://forum.kitz.co.uk/index.php?topic=1510.0Then go to the bottom of the page on this link and download the free version and then install it onto the C: drive, "Vista installation" and configure it from there.
"It can only be installed on the one "C" drive."
http://download.cnet.com/EasyBCD/3000-2094_4-10556865.htmlBasically, EasyBCD detects your operating systems then gives you the option of which one to boot in to as the default, or to interrupt the boot up to chose the opposite operating system "the interrupt time can also be set in EasyBCD"
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Edit
Just a thought and eventually if you can, will you please let me know the answer!
With dual-booting XP and Vista it loses the restore points "which is a known fact"
I am wondering if duel-booting "Vista and Windows 7" has the same result.
http://forum.kitz.co.uk/index.php?topic=1767.0Unfortunately my systems all have XP and am unable to test vista and windows7.