Well, the major point of tapes is that they are easily removable to be put offsite in case of a catastrophic failure. If you don't want to do that, you can still use a real backup solution to write to disks instead of to tapes.

One of the problems with using something like xcopy is that it won't back up any of the special system files. If it's just data that you're comfortable simply moving to a new machine, okay. It may also have trouble with "open" files; I'm not sure about that one.

Honestly, I'd go with a real backup solution. These homegrown things always fail. I'd go with a tape library, too, but a big enough library to deal with 600GB is going to be a hell of a lot more than a remote file server of the same size. Then again, ClearChannel isn't exactly cash poor. But I bet they're cheap, huh? I'd guess that a copy of Backup Exec and an 8-tape LTO-3 library would cost you about $7500.