Thanks for the advice everyone. I just created a playlist with varying songs from 96 kbps to 320 kbps. It should be interesting to see what happens when I test them out.
Just listened to Nights in White Satin @ 96 kbps with my crappy Maxell NB-303 I can notice how it's unclear and choppy.
Walking in Memphis @ 112 kbps with NB-303 sounds ok, nothing spectacular but it's actually not that bad. It's a little choppy at some parts; especially at the end it's quite choppy. Not as unclear as 96 kbps though.
Money for Nothing @ 128 kbps (with a better bit rate and great headphones w/amp, I think I would have an orgasm with the beginning of this song) with NB-303 it sounds pretty good. A little fuzzy in some parts but for the most part it's clear and not choppy.
That's all I listened to for now, and already I can notice a difference between 96, 112, and 128 kbps, however, I have very little 96 and 112 bit rate songs. I think I'll be able to tell the difference between 128's and 160's, 196's, and 320's with the PX 100 but I don't think it will take too much away from my listening experience.