Ultimate has a few features Home does not - such as bit locker data encryption (if your mobo supports it), remote desktop connection I think is absent on Home, the animated desktop, may be a few other goodies of marginal value. Vista business has the business oriented features Home does not but lacks Media Center.
The bottom line is that Home is very powerful and is not considered inferior to Ultimate in the same way XP home was compared to Pro. Networking should work great. If there are some networking features that you might ned in a large enterprise environment that are missing in Home that would not surprise me but I am not sure.
Business is a great alternative to Home if you don't need Media Center.