If you end up with a Sony Ericsson, get the free software Float FMA, which lets you synchronise with your computer and transfer SMS messages etc to the computer, backing up numbers; using the phone as a remote control to control your computer and so on.
Obvious place for specs is the Sony website, i think it's http://www.sonyericsson.com.
The 2 phones I mentioned play MP3s as well as games and taking pictures. The only real difference is the one with the better camera is slightly bulkier and not as nice looking. I think they both take memory cards, and you can buy 2gb memory cards from http://www.svp.com (also the best place to get blank media - they stock Taiyo Yuden discs! Very quick shipping too).
Hope that helps you, and anyone else reading.