As long as you don't power the old server back on after you remove the storage, and you don't sign or otherwise modify the disks while they are in the 2008 box, you should have no problem seeing them if you put it back in the old server.
As far as the probably of seeing them on the new box, I'd say it's ~80-90%. Sometimes windows gets flaky about drives full of data just "showing up", but mostly it's ok. But yes, definitely you'll have to fix the drive letters, that's stored in the OS, not the RAID controller.
HTH,
exx
