Well I've been using my Treo as my mp3 player for a couple of days now and I think I may have jumped the gun a little. It's still pretty solid, but I have two major complaints:

1. It can't stream anything over 64k
2. Sync'ing from iTunes, is turning out to be a little bit of a pain and kinda slow. I have to pretty much take the tunes I want and drag them into the Treo sync tool. There is no way to just hotsync and take the files out of an iTunes playlist. And if I copy the same file, it'll put two copies on my Treo.

This is really an Apple iTunes issue. The only player that seems to sync with iTunes is an iPod. Gotta love how Apple makes their products "kinda" work with the non-apple world.

...and my 1GB card is definitely not going to be enough.