Mac Server to authenticate Terminal Server users

[knyght]

I have a Mac network with Xservers running Tiger, LDAP doing all the authentications, and Ibooks (also Tiger) for the users. My users are mobile users if this matters. The Ad department needs to use the latest version of IE (6 or higher) to view certain websites that have active X stuff in them and that obviously is not available natively on Tiger. We have a Windows 2003 server (that is not doing anything yet) that can run Terminal Server for 5 people.

Is there a way I can have my users use the MS Windows Remote Terminal client software to access the terminal server using their same credentials from LDAP? They do not need any home directories or anything else fancy like that, just needs to say the Ad group can get in but the Market group can not. I have tried making the Xserver the primary domain controller (seems to work so far), I just want to do that with out the home directory binding stuff.
Budget keeps me from going to Parallels+XP and I have not found anything that will make Firefox or Safari able to see these types of sites.
Any hope?