Hi Mike,
I don't know about imaging or servers, but for our P2P network (about 10 work stations), I set Adobe Acrobat update on automatic and AVG update every night at 2AM. I tell everyone to restart their workstation every night. This takes care of those updates and any required restarts.
For the Java & Windows Updates I don't update very often. If I happen to be at another workstation to fix something I'll click install these updates. I haven't had any problems with Windows not having the most current update (but our computers are pretty new).
We don't update Flash. Not sure it's even installed. I don't update MS office either.
I don't want to start messing with imaging. Even though all the computers are the same, I still get a unique problem in one. I tried to create a backup image before but the size was humongous - could not save it on a DVD and I didn't want to take up all that space on our server. When we get a new computer or have to reinstall Windows (this has only happened with our old computers which are now all retired), I just sit there and install all the software. One thing you could do is copy all of your software install files to a server. Then after you've installed/reinstalled Windows, install Logmein right away; then log in from home open those install files.
PS. I took Bert's suggestion before to give your staff user name(s) administrator rights so these update can take place when they're logged in. They don't know they have admin rights and for our staff, no one is savvy enough to go looking and changing things in Windows.