Thanks again to everyone for all the great suggestions. This has turned into quite the general computer security and maintenance thread

. Really, all I was wondering when I first posted was if anyone else had seen this with the F@H software.
Final update: It's solved. RAM use goes up when I load something but then drops down again after a while. It must have been the accumulation of temp files. I'm going to be deleting them and defraging monthly from now on, instead of waiting until I have issues.
For anyone who is not familiar with deleting temporary files, the easiest way I know to do this in Win 7 is to use 'Disk Cleanup'.
Open Windows Explorer and find your 'C' drive. Alternatively, you can click 'Start', click 'Computer' and you will see your 'C' drive.
Right click on the 'C' drive.
Left click on 'Properties'.
Click on 'Disk Cleanup'. The Cleanup widow will open. Wait for it to do its calculations. It takes about a minute on my machine.
Scroll down the 'Files to Delete' window and make sure 'Temporary Files' is check marked. Un-check all others unless you know
for sure you want to delete those files as well.
Click 'OK', then 'Delete Files' and it will be done.
I think Disk Cleanup is in all current Windows versions. Mouse clicks will probably be slightly different getting to it and maybe using it, but Google and Window's 'Help' system are your friends here. I do not consider this a risky process.
Defrag is accessed pretty much the same way.
I always assume something could go wrong with the drive when defraging, so I back up my data first. I also have the operating system backed up, so I can reinstall Windows if necessary. If you do not do this you could lose everything on the drive with no way to restore it if the defrag goes bad.
Find the 'C' drive again and right click on it.
Left click on Properties.
Click on 'Tools' at the top'.
Click on 'Derfagment Now'.
Highlight the 'C' drive and click 'Defragment Disk'. It takes a few minutes to go through the process.
If you have more local drives, work through the others one at a time. If these drives don't see much use, they will defrag very quickly.
Again, don't defrag if you are uncomfortable with the risk. A power failure or an underlying problem with the disk could make your computer un-bootable until it's fixed and everything not backed up will be gone.