Upgrade to NetWare 5 or Microsoft

Hi,

I am a new member, and I administor networks for a bunch of real estate offices. They are currently running NW 3.20, but need to upgrade since NW 3 is pretty much obsolete, and they need to add users.

The question is, should we go NW 5 (Small Business Suite) or Windows (NT or 2000 Server)?

Pros and cons would be appreciated. I am cross-posting this to the NT forum as well.

Thanks for your help.

Don