Need help upgrading my phone

[ElAguila]

I am getting ready to upgrade my current phone. I currently have a Sprint PPC6700. It is still a good phone but I need another phone and I am going to use the upgrade rebate to get a second phone. What I am looking for is a phone that allow me to play mp3/wma music as well as create/edit contacts, appointments, and tasks with the phone and then sync it with outlook 2007. I would like to be able to access the internet with this phone. I would also like it to have a microSD expansion slot capable of at least 4GB and I would like one that has a hard case available for it. The aluminum case that I carry my ppc6700 in has saved my phone many times from breaking. While I would lke for it to have WiFi, it is not a requirement. I like the way the htc pro looks, but I really don't need that much functionality beyond what I listed and it is a more than I would like to spend.These are the phones that are in the price range(after the rebate) that I am looking at. The carrier is Sprint. While I am researching them as well, if you have had experience with any of these I would like to hear your recommendations on them:

Centro by Palm(new model)
Treo 755p by Palm
Moto Q 9c by Motorola
Samsung ACE