Well, delving into Apple strategy for a moment, I believe they're positioning the iMac for a consumer computer that has no upgrade option in mind. A customer that purchases an iMac most likely would not be someone that performs upgrades to their computers in the first place. Apple does have the PowerMac line, which follows a more traditional PC route that allows for upgrades to the computer. With that said, you can still upgrade the Airport card and memory for the iMac.
About the casing, I'm not sure on that issue either. I'm actually tempted to side with you on this issue. I remember several articles about how the Cube (similar small form factor, fan-less) had trouble with heat dissipation.
Now, to return this thread back to its rightful owner
... Our robot has an omnidirectional holonomic drive platform. We'll just be scooting circles around the field. (However, I have a very strong feeling that it's going to break down, but we're trying out a lot of new ideas this year.) It'll be really cool if it works and still moderately neat if it doesn't.
