Another thing is to try changing processor scheduling to 'background services' (and other performance settings): Right-click on My Computer and select Properties, then click on the Advanced tab (or click 'Advanced System Settings' on Vista and higher).

Here’s some other things you can try:

Click on the Settings button in the Performance section, and select 'Adjust for best performance'. Your operating system will not look as pretty, but will be faster.
Try setting Processor Scheduling to 'Background services' rather than 'Programs'.
You might get better sequencing if you set Memory Usage to 'System cache'.
The previous two items might be most noticeable if you have a specific problem you are trying to fix. If toggling those settings doesn't help anything, or makes matters worse, toggle them back. However, most people should get at least as good or better performance with 'Background services'.

Another thing that some people find helps is to click the [Change] button in the Virtual Memory section, and select 'Custom size' rather than 'System Managed Size'. System managed is the safest setting, so most people will probably want to leave it there. However if you do set it to Custom, try setting the Initial Size to the size of your RAM (for example 6GB) and the Maximum size to twice the size of your RAM.

Best,
Chantelle