Congratulations on your new 650. I'm sure you'll find the forums and the Everything Treo e-News as a good source of information. If you plan on using iCal, then you'll be using iSync. Definitely check out the
Mac OS X and Treo forum. There is a lot of information there and feel free to post any questions you might have. If this is your first Palm device, then you'll have plenty to mess around with in the early going. I assume you've got a data plan with T-Mobile -- with your Treo, you'll be able to set schedules to check mail, surf the web (mobile sites such as
Treomobile.com will work best). I'd definitely recommend checking out
Mark/Space Missing Sync -- fantastic software for the Mac. Not only does it ease the sync process, it also allows you to mount your SD Card -- and have full integration with iTunes and iPhoto.
Not sure if T-Mobile would insure a Treo 650 -- considering they don't even carry it -- but I'd look into it. Either way, get yourself a good case -- if it's open faced then screen protectors are a good investment.
IMHO, one of the best things about the Treo 650 is bluetooth. No more wires. There are a number of headsets. I prefer the Sony Ericsson HBH-660. If you have questions about a headset, then you can always ask for feedback in the
Bluetooth section of the forums.
Suffice to say, there's so much you can do with your Treo 650. Take it slow -- and enjoy the ride.
-Chris