I'll try... but I haven't really got a good idea...
I am not seeing how to change the MP3 conversion rate anywhere.
Right after the progress bar that says "mixing down audio" finishes, there should be dialog box with a few settings you can adjust.
When I mixdown, I save files in a folder I made called music, and I think the culprit is that they are being played back in Realplayer, which I know nothing about. Should I save in Cakewalk instead?
You really aren't a computer person, are you?

I don't think RealPlayer has anything to do with this. When it was installed it associated the MP3 file extension with itself -- that way a Real Audio icon will appear in the directory list and if you doble-click on the file name, it will open in Real Audio. You
did save it in Cakewalk.
I just tried a file. It is about 35 MB 44.1 kHz, 16-bit stereo. The MP3 Cakewalk made is about 3.2 MB encoded at the 128 kbps.
2 minutes of stereo WAV should only be about 20 MB. The MP3 encoded at 128 kbps should be about 1/10th this size.
If you really have a giant mixed WAV file then something is hosed in Cakewalk. Does the giant WAV play? I would think it
must be corrupt in some way and shouldn't play at all. Unless it's like 75 copies of itself back to back...
Are you
sure it's not a bun file that's that large? It's
really a mixed-down, stereo, 44.1 kHz, 16-bit WAV file?
If you saved as an MP3 at the highest possible quality (that is, virtually no compression), it might indeed be close to a mixed-down WAV file in size. So maybe you're looking at different files than you think you is...??
I made a file of two minutes worth of music, stored it in a new file, and it says it is 151,800KB. I would assume that means 15MB?
That's
151.8 MB. A megabyte is 1000 kilobytes.
Oh, and keep the Cheney photos and Brad's mom for yourself, you'll need 'em when you get out of this fix.