Now that I've joined the iPod family, I have a dilemma. My current music collection (all ripped from personal CDs) is strictly 128 kbps MP3. Alas, it won't all fit on my 40G iPod, as it's about 45 GB total. It will, however, fit if I re-rip to 96 kbps AAC. Since (I'm told) audio quality is comparable, and I don't really use the iPod in critical listening situations (gym, plane, car), I'm okay with 96 kbps AAC. Obviously, re-ripping 40 GB worth of CDs is a fairly massive effort, so I'd like to get this right. And I can't completely eliminate the MP3 format, since my home listening is with a Turtle Beach AudioTron, which doesn't support AAC. So, it seems like I have at least three ways to proceed. Comments and advice on any of the following are appreciated:

1) Rip everything at 256 kbps MP3 only, then use iTunes to convert to 96 kbps. (Some quality loss at 96 kbps, but is it worth worrying about? Also, is AAC tagging any better than MP3?)

2) Rip everything at 256 kbps AAC, then convert to 128 kbps MP3. (Higher quality "masters", but it locks me into AAC more.)

3) Rip everything at both 256 kbps MP3 and 96 kbps AAC. (Best quality in both formats, but gosh it's a lot of work.)