If your Vista computer is feeling a little sluggish after being up for a while, a thing that sometimes helps is clearly the memory cache. This helps free up unused RAM, and having more available RAM can make your computer faster. For me, I keep a shortcut to this command on my desktop so that whenever I need it, it's just a click away.

To create this shortcut right click your mouse on an empty area of your desktop and select New -> Shortcut. When you are asked for the location of the shortcut, enter the following:

%windir%\system32\rundll32.exe advapi32.dll,ProcessIdleTasks

then click Next. You can then assign a name and an icon to the shortcut. Next time your computer feels slow, click on this icon to free up available memory and hopefully your computer will be faster afterwards.