Windows Vista is a resource hog, but turning off unnecessary features can help make a difference.  Do you really need the network icon in your system tray to flash whenever you send or receive information, for instance?  Enabling this uses some CPU time and loads an extra Vista component, swallowing up a little memory.  If you can do without it for a while then right-click the icon, select “Turn off activity animation” and you’ll recover the RAM immediately.

If you don’t use ReadyBoost then that’s an even better candidate for removal. Click Start, type services.msc and press [Enter], then scroll down the list and double-click the ReadyBoost service. Click the Stop button to free up any RAM it’s using right now, set its Startup Type to Disabled and the service won’t be started when you next reboot, leaving more memory for the applications and services that you actually use.