Monitor Users on Ubuntu Lucid

[Matus]

Have 3 computer labs ... Out of these one is used as general purpose lab during evening hours...
During these hours I'd like to monitor their time spent on the machines logged in, after 40 minutes log time they should be kicked out. ALso printing should be limited to 20 pages...

What would be the best approach to something like this ? Users log in via ldap, samba shares, and one cups machine.

Server Ubuntu 8.04 Hardy
Clients Ubuntu 10.04 Lucid

[bernt]

Not too familiar with administration stuff, but I'm good at finding software!

monitor their time spent on the machines logged in

https://launchpad.net/timekpr

ALso printing should be limited to 20 pages...

Print quotas are supported in CUPS directly. Take a look here for a short howto.