Joining Ubuntu client to Samba PDC

Hello don't know if this has been asked before, if so please provide a link.

I've gotten a little experience with Linux/Ubuntu and I'm loving it! I work for a school and I have used Ubuntu 11.04 Server to be a Samba PDC, I have been able to add Windows XP and even Win 7 clients. Each student has their own username and password. They have their own H: drive associated to their login. In other words Ive enacted roaming profiles.

Now the problem I'm facing...

Since we have some older laptops that aren't met by our district warranty I am planning to add Ubuntu Desktop/Laptop edition to it (hey it's free and mostly everything is cloud-based, why not? LOL). I am having trouble as to how to add the linux client to the Primary Domain Controller that way the students can sign in with this linux client and keep their files in their "roaming profiles" just like how they are able to do it with Windows clients. Yes I want to have them use the same username and password to have them sign on to the linux clients.

Any ideas! Thanks!