Hello,
My computer has recently started telling me I need to save my files because memory is running low. What does this mean? I have 4Gb of RAM and a Nvidia Quadro 3500 graphics card that I use for my Maya 3D application and Photoshop work. The computer just started doing this ever since I connected it to the internet otherwise it was fine for the last 3 years and has had no problems other than my adding more Ram to it (went from 2Gb to 4Gb). Can someone please help me? Virtual Memory and RAM are not the same thing.

Virtual Memory is usually just referred to as a Page File, when you get errors like that it usually means that you are running out of space on your Hard Disk.
You will need to FREE up space on your hard disk by either MOVING files to a different drive, or REMOVABLE medium, or you will need a new and larger Hard Disk. If budget is a factor then just move the files off of your C:\ and free up more space.

One thing to look at is if there are any PROGRAMS installed that you do not use, uninstall them.Do not confuse memory with hard disk space. If you are running out of space for files, that's hard disk space, not memory. "Virtual Memory" is the use of hard disk space to AUGMENT ram.