HighMem

I want to know if there is a Groupware (or, at least, something that is not called Groupware but does what I want) which has the following features:

1. Beautiful, efficient and comfortable web-interface
2. Low resource usage (server RAM and CPU)
   
3. Calendar is iCal/WebDAV accessible
4. Contacts are LDAP or (even better) WebDAV accesible (GroupDAV, what are you?)
5. Uses Mozilla Thunderbird as client (it's nice and portable)
6. Can synchronize contacts and calendar with cellular phone (syncML)