Question : Remote Desktop Connection to Windows SBS 2008

I have attempted to connect to my Windows SBS 2008 via a Remote Desktop connection from my windows XP PC, I am able to get to the window to the remote connection to the Windows SBS 2008 server, however when I input my user name & password a message keeps appearing "the username or password is incorrect". I am 100% sure my password is correct.

What could be causing this problem and how can this be resolved ?

Answer : Remote Desktop Connection to Windows SBS 2008

and you can logon with exactly that user/pass in another machine?

entered domain\user as username?
just in case: capslock, numlock activated?