Plugging a usb thumb drive into a USB port will also boost Memory in Win7/ Vista
Generally get a USB drive same size as your existing Memory as a minimum.
Win7 systems with 4GB or more Memory may not notice a difference.
Plug it in and the pop up box has the option for 'ready boost'
Info & how to:
http://www.vikitech.com/9683/readyboost-usb-drive-improve-windows-7-speed
I wouldn't touch GameBooster unless you know the things that is is doing. If you are not PC literate, stay away. Too many horror stories.
Use this guide to disable unnecessary Services
http://www.blackviper.com/service-configurations/black-vipers-windows-7-service-configurations/
Use CCleaner,
http://www.piriform.com/CCLEANER
to clean up system rubbish and within the TOOLS section there is a START UP section. Disable programs you don't NEED to start every time windows runs.