Odd connection problem

I recently added a new wireless Laptop with Vista to my home network which consists of an XP laptop with a wired connection and a computer called "server" running NT 4.0 with two printers attached to it. All are connected to a Linksys router.

Naturally I need the new Vista laptop to be able to connect to "server" so it can print. All three computer can "see" each other on the network. When I use the XP laptop to open "server", it brings up a login screen in which I must enter username and password. When I do, it opens the computer and I can see the two printers.

However, on the new VISTA laptop, I get the login screen -- but when I type in the same username and password, it tells me the login is not correct. What gives? I think I have everything enabled on the new Vista laptop, so I am baffled as to the problem. Note-it is not a case sensitive problem, I am typing the username and password exactly the same.