If you can get enough free unallocated space with Partition Magic, then let your linux installer configure it's partitions in the unallocated space (automatically set up swap partitions, root and other partitions if necessary), it should be a breeze. Partition Magic has saved my ass multiple times in moving stuff around. Remember though if you move a partition past the 1024 boundary, it will NOT be bootable, as stated in partition magic. Make sure whatever partition your bootloader resides on is within that boundary. Otherwise, you might be able to install, but your BIOS wont see the boot partition if it's on the end of your drive. Just a heads-up there.