I didn't do a "Batch Rip" to WHS, but I did use three separate systems to RIP CDs to the WHS symultaniously - there didn't seem to be a problem. I had to be sure to have the Libraries in Media Player completely empty when I started, if you had a disk already listed in the Media Player library the system simply rejected the CD. After all the music was stored in WHS, I then had to completely empty the Media Player Library on each system and let it search and upload all the music again. I did all this with XP systems so Vista might be different.
Good luck....
LJ