mounting Windows 2003 share on SLES 10.3

[amesadm]

Hi,
We have a Windows 2003 server that uses Active Directory to authenticate users. What I am trying to do, is mount my user account on the windows server, onto my SLES 10.3 server, so we could back-up data files from the SLES 10.3 server to the Windows 2003 server. I am using Nautilus' URL box and specify the connection like this:
smb://172.20.1.2/

A dialog window appears on top of the connected server window (with list of all available shares on that server) whilst prompting for a domain name and my password. Even if I provided the right domain name and password, it would not allow me to get through and see the shares on the domain and exits while giving me an error.

Do I need to alter /etc/samba/smb.conf to allow connection to the remote server? Also, do I have to specify the IP 172.20.1.2 as a host.allow entity?

I'm at the end of my wits. Can somebody help me out, please?