I have bought a new dell server to run WHS and I bought a tape backup for the server but I read that WHS does not support this, my question is --can i pull the tape out of the server and put it in the client machine w/ admin rights and use it to back up? I have 2 clients and 1 server.
It's not so much that WHS doesn't support the tape drive. You just need to install drivers and software, and it'll work.
However WHS, because of the way Drive Extender works, doesn't support traditional backup tools in general. You may be able to run a backup, but attempting to restore using almost any tool may result in data corruption.
If you really need to back up the files on WHS, it should be safe to back up from and restore to the network shares, if your software supports that. But it's probably easier to just turn on duplication for all shares. As long as you have sufficient disk space, WHS will store two copies of any file in a duplicated share, one each on two separate drives. That way you're protected from any single disk failing.