I have a windows 7 and an xp machine. With 7 it's pretty easy to see whether you have enough memory or not (open task manager and see if you have significant amounts of "unused" memory) but with xp ...

Hold on. Don’t just reboot your Windows 7 PC. I realize that rebooting is the go-to solution when a program won’t shut down, or the system starts dragging or acting wonky, but there is another way.