I have been given an oldish/slow PC, that was destined for the skip. I believe the guy who gave it to me, originally got it from Noah, before he sat off for Mount Ararat.
I've decided to give Windows and all it's update problems the heave ho! Instead I'm installing a system that was designed specifically with old, slow PC's in mind. It's 'Open Source' software, so it doesn't cost anything either. Its 'Puppy Linux'.
Obviously you aren't in the position to change the OS in the systems you are referring to. But if they are old and slow I don't really think anything you do to a Windows based OS is going to speed them up for very long.
The machine in question is a Gateway. Before I decided to take this radical step, I did a clean install of Windows. It was quite swift, until I started re-adding the necessary extras. Now it's almost back to square one. When I was give this PC the previous owner threw in a 10GB HDD. Actually I have a memory stick with 8GB. But as Puppy Linux only needs 100MB, I'm going to install it on this drive.
After I've put it through it's paces I'll post a thread with my findings. Another good thing about it is, you can install it on as many systems as you want for NO cost!