Ubuntu Servers :: Samba To Replace Windows File Server In Active Directory?

We have a couple of Windows file servers that just share files. It is all they do. We'd like to use Ubuntu on two replacement servers allowing Windows XP and Windows 7 clients to access the files. Our network is active directory based due to Exchange and homegrown .NET apps, so it is important that active directory is used to authenticate the clients. Samba doesn't need to be a pdc or bdc, but provide pass through authentication.I understand that Samba can communicate with active directory through security-ads and security-domain.

Here are my questions to see if I should proceed:1) Folder permissions:If we move all our files to the Ubuntu server how do we set folder permissions and will we see the active directory accounts when we do this?2) Skipping ubuntu accounts: I know the domain and ads allow you to skip creating ubuntu accounts, right? If not, how do you keep the passwords synchronized?3) Easiest way? Is there a very easy way to pull this off that I've missed? My goal is to eliminate the Windows based file servers while ensuring the admin part of it is as easy as possible.To date I've been able to get the sharing to work with an ubuntu account mirroring the active directory account. I've been able to get Samba to talk to the pdc, but not successfully through domain security. ADS security was a complete cluster with winbindd