Along with providing IPV6 as a default network protocol in Windows Vista, Microsoft made another major change to the protocol stack there - they eliminated the optional IPX/SPX selection. Microsoft now does not support IPX/SPX, in any way.
Windows Vista does not provide a NetWare client or the IPX/SPX protocol.
You can get a Novell client, from Novell. We haven't confirmed that this is IPX/SPX, though.