pjhealy
The area that I'm most unsure about is the creation of 'groups' in the SME administrator tool; will I be able to assign XP Home users to a group and still be able to limit access?
XP Home does not allow you to join the workstations to the domain, so there will be no "trust" relationship between workstations on the network ie you won't be able to automatically see shares on other workstations etc.
As it does not support domain logins, then it won't allow you to automatically run the netlogon.bat batch file at login.
You can map network drives (shares) though, either manually or with a batch file that runs on each workstation at startup, rather than on the server.
The important aspect of group access rights, is that each ibay is owned by a different group (usually), and users are then made members of the appropriate groups for which they have access rights. Even though users can still see the share names/ibays from workstations, they will not be able to access shares/ibays for which they are not members of the group that owns the ibay.
Groups can also be used to create email addresses that send the same email to many sme users.
Please read the manual again especially re Groups and Ibays.