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if /dev/sda5, is the windows installation partition
in grub that relates to 0,4 sda=drive0 and partition 5=4 (grub starts counting at 0,
(like any good computer science))
But the partitions are all over the place, if I may, I would suggest repartitioning the
first HD so that vista is on sda1 (with room for the master boot record), then an
Extended partition at sda2, which is not really used but is a locator for older
M$win file-systems to find other partition entries.
I mean, in my experience, GNU/Linux does not care about extended partitions,
but can use them if you insist.
Vista will expect to be on the first partition of the first drive.
If you ever have to repair that file-system, you may find it very difficult
(but, I have never tried it with vista) It probably works OK as is,
but it's not good practice.
as for the others, same goes with Extended partitions, it's a left over
from dos days. But it will work.
sdb looks like the Linux install...HD1
That looks like an awfully large swap file, generally, in my experience,
your swap needs to be large enough to cover your ram. I generally make mine
a bit bigger if I have the disk-space. Like a dvd size.
Make a really big /home partition too, so it will be safe if you have to reinstall Linux
(for some strange reason).
sdc1 may be the Mac hfs+ partition.
If you don't have too much personal data to risk, go ahead and
re-partition and reinstall vista, but if you have loads of stuff you don't
want to delete, then copy it to the Linux partition first and move it back later.
I'm not sure about the rest, but the layout of your partitions, especially the sda1
extended partition, may be the cause of grubs confusion.
There are many good grub tutorials around here, but I think you need to re-organise
the partitions first, so there is room for a master boot record and the rest.
But if you change this, it might work.... no promises though.
This looks right...
title Windows Vista
savedefault #don't know about this line
anyhow, see how you go,
ps, does your Debian install disk (cdrom or dvd) have a rescue mode in the boot menu? If so, you may be able to reinstall grub from there, it will (should) find all of the boot-able file-systems (drives) on your system and place them in the new grub menu. easy as!