If you have a bunch of mp3 with out DRM, (they play on your computer on any old mp3 player like winamp) and mp3 ripped from CDs, and you aren't looking to get tied up to a downloading service that uses a DRM, then go for something like the CL Zen 30gig or 20gig player.
More bang for the buck compared to IPods where the Apple name is demanding more $$ per bang. I don't know if the Zen still has a user replaceable battery, but that is something to look for.
Apple has a huge following, and they did a good job with ITunes, but the actual IPods aren't (IMHO) as good as people rant about.
Technically IPonds have an odd way of storing files on the hard dive, they segment the mp3 file into pieces , then store the different pieces in different encrypted directories, to keep people from hacking into the IPod and pulling files off it without ITunes and bypassing DRM. So if one of these thousand segmented directories drops a bit - you "loose" every song on the IPod.
This is why IPod has a higher frequency of "wiping out".
On a file system that contiguously stores a single file, of you loose a bit, the one song gets a little muffed up or becomes a bad file. On the IPod, all the files take a dump cause this linked, but segmented file storage architecture takes a dump when one link the in chain becomes bad.
KISS, is not what Apple followed for the file storage system.
IPods tend to have, more than others, battery problems.
Not that others maynot. But based on my friends that use them, IPods more frequently do.
I have to admit, no other device has such an aftermarket of accessories either.
If you plan on using a pay downloading service with DRM, you may first want to see what devices they support.