Question : Windows 7 - Lock PC after a specified idle time

We are upgrading to Win7 from XP and are desperate to ensure that a PC lockdown policy is deployed at the same time.

1. Lock the PC with a screen saver after 15 minutes idle time. User can unlock with their windows password.
2. If the screen saver wait time is less than 15 minutes leave unchanged
3. If the screen saver wait time is higher than 15 minutes change to 15 minutes
4. users can change the wait time  (rules 2&3 will enforce the policy)
5. if no screen saver set, apply above policy
5. meeting room presentation PCs to have different wait times

How can we do this, we tried Group Policy  but this sets the wait time to 15minutes and cannot be changed to a lower number by the user.
With XP we use a script but i am told that it cannot be used with Win7
How can I solve this problem
Many Thanks
stavrinc

Answer : Windows 7 - Lock PC after a specified idle time

Does your BIOS give you the option to select between integrated Intel GMA graphics and the Nvidia graphics adapter?
Then you should try with Nvidia disabled.

If that isn't possible, check this for advice: http://blog.triumphovermadness.com/2010/05/ubuntu-1004-lts-on-hp-elitebook-8440p.html