Solution: This occurs due to a service running on Vista called "SuperFetch". The SuperFetch service in Windows Vista preloads your system’s memory with the applications that you use most often. This makes launching of those applications much faster. I have not experienced any slowdowns after disabling the service and my disks are resting while the system is idle (or not used heavily).

Here are the steps to disable it:

1. Open up Services in Control Panel or by typing services.msc into the Start menu search or run boxes.
2. Find SuperFetch and Double-click on it to open up the properties
3. In the drop-down, change "Automatic" to “Disabled”. (If you don't want to reboot immediately, click on the Stop button as well)