Windows XP uses a file called hiperfil.sys to save everything it needs when Windows XP goes into hibernation. If you are like me, and never use the hibernate function, you can turn it off. By turning hibernate off, Windows XP deletes the hiberfil.sys. This can free up the as much disk space as the amount of ram that you computer has.
Go to Control Panel/Power Options/Hibernation and untick the box. It's as easy as that. Now you will have plenty more disk space to install those mega programs!