What are your render settings? Composition size? Output format? Render settings? What does the composition contain? What source footage and effects are used?
Mylenium asked very pertinent questions. I'll make some educated guesses, which may or may not apply.
First thing: 2 GB may seem like a ton of memory to you, but in AE-Land, it's NOTHING. You need to trick that machine of yours out with memory. On a 32-bit system, that would mean bringing it up to 4 GB.
If you're trying to use multiprocessing, turn it off and leave it off. On a 32-bit system, you'll never have enough memory to make multiprocessing work efficiently.
Trying to speed rendering by using Open GL acceleration? Turn that off, too.
Since you're on a 32-bit system, the most recent version of AE you can run is Version 9. Make sure it's fully updated.
But if you shot video on a DSLR, HDV Camera, XDCam or Flip Cam, you could still have problems. Since you can't be running AE 10, which pretty much solved the problem of long-gop footage, here's why:
Dave's Stock Answer #1:
If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, AVCHD, mp4, mts, m2t, H.261 or H.264 -- you need to convert it to a different codec.
These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.
In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.
I'm a Mac guy, so I like to convert to Quicktime movies in the Animation or PNG codecs; both are lossless. I'll use Apple's Compressor, Adobe Media Encoder or Quicktime Pro to do it.