Laura and Shai,
thanks a lot for your suggestions! I think I'll go with separate installations then, as this seems the easiest way and I really dont have the nerves to risk potential showstoppers along the way.
cheers Morten
The simplest at this point would probably be to share a filesystem, if you want, but have different databases, then set up single signon. Splitting one site across several domains or subdomains can be complicated. The multidomain module does this, ostensibly, but can be rather tricky to configure.
If you do SSO in the arrangement you say, you wlll want to watch out for cookie collisions.
Laura