Low memory Problem Solution

If it's not a memory leak (see "Windows Slows Down) or other program hogging your RAM, you can try increasing your virtual memory, which is a cache that Windows stores on your hard drive. Right-click the Computer icon on your desktop and select Properties. (In Windows 8, switch to Desktop Mode to see the icon.) Click Advanced System Settings on the left. In the section labeled Performance, click the Settings button. Click the Advanced tab and click Change.
Uncheck the box at the top and select Custom Size. A good rule of thumb is to set Initial Size and Maximum Size to 1.5 times your amount of RAM (listed on the Properties window you opened earlier). More than that can actually slow down your PC. Click Set and then click OK.

Editing high-def videos, high-res photos, or large audio files can eat up gigs of RAM, too. If that's something you do, adding more RAM is not a bad idea, assuming you have available slots on the motherboard and you can find sticks of the same type and speed.