I have XP on the first partition and Linux on the third. I want to re-install XP. If I copy the mbr to a file on my Linux partition, re-install XP then copy the file back to the mbr (using a live CD) can I be reasonably sure that I can reboot? In other words will XP install only to the existing NTFS partition or will it take the whole drive?

Thanks.

If you do a 'clean install' XP will hog the lot and parts of Linux will undoubtedly be damaged (especially if the NTFS format zeroes the HD). Maybe a "fix" or "update" option would keep the disk partitions intact. If you have a spare disk, you can move Linux there at least temporarily; also record how the partitions were set up (fdisk -l) so you have some idea how much to shrink WinDuhs later on when you copy Linux back.

Clean install.

The XP installer can only see Windows formatted partitions (FAT16, FAT32 & NTFS), so as long as you know where the current installation is then you are OK. Say the XP system is on C: drive, then when you get the choice select that. If you are doing it from a recovery disk you most likely won't get a choice and it will go on C: anyway. I've done this with Win2K & XP a number of times, and the only hassle is putting GRUB back. During the install you need to let it put it's boot loader on the MBR so that it can reboot automatically after each stage/driver.

So, yes make a backup of the MBR, to a usb stick or whatever, install XP, and then use a Suse Live CD, or PartitionMagic to put it back.

Alternatively after installing XP, run the Suse Installer CD (preferably from the same source as the original install), and when you get to the page which allows a choice of New or Upgrade Installation, choose Other & select Repair, and then Bootloader (the actual wording may be different, as I can't remember it exactly). This will run the same utility as YaST and will find your installed OSes, and offer you a new Boot menu which you can install to the MBR.