I have been using partition magic for several years now & have always used it to set up the hard disk for multi booting systems before installing any OS or boot manager. You have to ensure that the partitions are aligned to the cylinder boundaries otherwise you might run into problems. So far I have not run into compatibility problems unless the bios on the machine you shift your hard disk to does not support the full size of the Hard Disk.

For past year or so I have changed to BootItNG which is an unbelievable application allowing you to have any number of primary partions & resisizing / moving + a full fledged boot manager.

Try out the trial version from www.terabyteunlimited.com . You will love it.

One note of caution though, on very large hard disks the process of moving /sliding might be time consuming.