Why does after effects take so long??
 

I'm rendering a video in AE as uncompressed AVI; the video has NO effects and there are two layers. It is 13,000 frames. Why is
it rendering at 1 FPS?? It's really frustrating

Specs are:
Pentium 4 2.8 ghz processor
512 MB RAM.

I'm no computer genius, but I can tell you for sure, that 512MB memory is pretty much the bare minimum for running xp with no programs running, never mind After Effects, which is one of the most memory intensive programs you'll ever run on windows!

Go out and get yourself at least 2gb RAM and you won't believe how fast your computer becomes!

Mel, Chris pretty much spelled it out. 2/3 of your memory is used by Windows. The remaining is used to load AE. You basically have no memory to process the clip. You will need 1GB per video application, at least, plus at least 1/5GB for the OS. If you have plugins, they will take more memory.
This is, BTW, one of the reasons why Mac have the reputation of being more expensive than PCs. They are actually cheaper but come with higher defaults so their price is higher than your typical budget PC. As Chris said, add 2GB and your rendering will be much shorter.

The issue of not enough RAM is definitely something to think about. Before I beat the proverbial dead horse though, what's on the second layer in your comp? If you have any effects or complicated stuff going on there, that would add to your dilemma.