I've always wondered, when ripping CD music to my computer, just what do bitrates and burning speeds determine?

I know that higher bitrates and slower burning speeds yield better quality, but in what aspects?

I've been considering ripping back my entire collection as 320kbps MP3s, since I have both the room on my computer hard drive and MP3 player, but how much better quality would it yield versus 192kbps MP3s?

V0 is the best. 320 is overkill, and if you can actually hear the difference, you might as well use lossless.
How large a difference over 192 would depend on the quality of what you're listening on.

The burning speed you use when ripping a CD makes no difference. If anything, EAC will manage this itself and use the most appropriate speed. When encoding your WAV files into MP3 format there are a few golden rules to abide by;

1) Always use a recent LAME encoder (3.97 or later will be fine)

2) Unless forced to, by hardware limitations or something, never use CBR. I'd suggest using either V2, V1 or V0 depending on your quality needs and space limitations. You can read more about this here. The reason to use VBR is because the encoder will then choose the most desirable (using quality vs. size) bitrate [between 32 and 320] for each individual frame within a file, instead of using a set one for the entire file, thus optimizing quality.

Burning speed and ripping have nothing to do with each other. One is writing, the other is reading. Just make sure youre using a cd ripping tool that supports secure mode.

If you're using PC speakers, then this command line option in Exact Audio Copy: -V 2

will work just fine. The mp3 files sound good in factory car speakers, too.

If you're using really good speakers or headphones ($2000+), then just use the original discs, if possible. That's why I keep wav files around now.