Question : Best method for automated use of Defrag, chkdsk, Disk cleanup, etc.

I help mantain a school network of 550+ desktops throughout four locations.  Up until now, during summers the above mentioned tools were manually run on each machine.  I've told my boss that we could free up a lot of time by having these things done automatically.

My original idea was to push out a set of scripts (using Group Policy) which would create scheduled tasks on each domain machine, and have the tools run on separate nights.  We run Server 2003 on our DCs, XP Pro on the workstations, and we have a mixture of Gateway E-2600S, E-2610s, and HP dc5800.

First question, do any of you have an easy way to go about it?

Second question,  will scheduled tasks run if:
A) No one is logged on the machine
B) The machine is in standby, but not turned off

Answer : Best method for automated use of Defrag, chkdsk, Disk cleanup, etc.

Scheduled tasks can run at the logon screen but it also depends on the program you are launching. We use Defrag as a scheduled task that runs on computers at night.

Here is the link to a VBScript to defrag all machines on your network.
http://www.dougknox.com/utility/scripts_desc/defrag_all.htm

Here is a script for Disk Cleanup.
http://www.visualbasicscript.com/m66923.aspx

Here is another link that also illustrates how to create a Scheduled Task via script.
http://blogs.technet.com/b/heyscriptingguy/archive/2004/09/22/how-can-i-manage-scheduled-tasks-using-scripts.aspx

I have also had success with PSEXEC by Sysinternals
http://technet.microsoft.com/en-us/sysinternals/default.aspx

Hope this helps~!