i had 10.5.7 running and have some software i got (through work) that is registered to that machine and i cannot reinstall on my new install. Im going to guess its because the uuid is different? because other than that my hardware is the same.

so im curious if thats it or if theres anything else i can do to make my new 10.5.6 look like the same machine as if it was a real mac that as upgraded.

Are you using the same SMBIOS as before? Could reinstalling have changed the serial number of your Mac OS? If you use Chameleon Bootloader you can define the serial number in smbios.plist (in /Extra)... These are just guesses as I don't even know what software you're talking about...