you have to turn off some of those programs running in the background
simply end task and exit all back programs running the back ground and check out your memory and resources.
Webroot is a real memory hog, it's a nice program put I'd exit it or disable it at start up
it really doesn't need to be running all the time unless you have a bad spyware problem.
you want to have you're resources in the at least 80% area IMO while idle.
if you want to limit your vcache just do it manually don't use a program that more than likely will use resources.
if you need to see available memory, disk cache size, swap file in use and more use sysmon that comes with windows 98 or you might have to install it in add remove windows setup system tools
also try using
regmon
a perfect 98 system when idle shouldn't have anything accessing the registry when idle
your AV will more than likely show up every once in a while but if something is constantly accessing the registry when you're not moving the mouse or anything then you should look into that because that more than likely is causing problems
also with regmon don't worry about the registry keys too much just pay attention to what is actively accessing the registry which means that program or file is agressisively running.