spgroup

How can I list all SPUser objects in a SPGroup?

I need to retrieve all SPUser's from a SPGroup. Unfortunately, the group may contain Active Directory groups, so a simple SPGroup.Users is not enough (I'd just get a single SPUser for the AD group, with the IsDomainGroup property set to true). Does anyone have a good idea how can I obtain a list of all SPUser's, descending into any Acti...