USB>SCSI adapter

I have a media server with only 2 PCI slots which are both utilised (one with a disk array and one with a tape drive). I'd like to add an additional tape drive on a separate SCSI bus, but obviously I've no spare slots to install a SCSI card into. Is one of these Adaptec USB2xChange USB to SCSI adaptors supported by BackupExec:

 

 

If they are, they seem to be discontinued, so maybe there is something better?, or even a better way of achieving this beyond buying a new server?

 

Thanks...

 

Mike