You are spot-on to first select a wireless carrier, then examine what they have to offer in terms of smartphones and mobile handsets.
Your approach to dual platform synchronization, however, is flawed and doomed to failure. It wouldn't matter if both platforms were PCs or both were Macintoshes: synchronization software is just not intended to support single devices as 'data carriers' between multiple Macintoshes. A far better approach would be to use…
• Outlook on your PC
• the latest version of Entourage 2004 on your Macintosh
• an Exchange Server to arbitrate data transfers between these applications, and
• the Sync Services framework to handle synchronization data between Entourage, the Address Book and iCal
If you want to synchronize to the Macintosh platform, you will need to add the Missing Sync for Windows Mobile [pre-release alpha 2.5a14 currently] to the mix. This application is Sync Services compliant, and will handle the synchronization of your Windows Mobile 5-based Motorola Q with the truth database, and therefore the Address Book, iCal and Entourage.
Or, you can synchronize with Outlook using a Windows Mobile device and your data will migrate through the Exchange Server to Entourage, and on to the Address Book, iCal, and iPod through iTunes, and other Macintoshes using either .Mac Sync or MySync. Just don't try to synchronize your Palm device with
both environments, or you will put your data at serious risk across the entire synchronization pool.
You can accomplish the same thing using a Palm OS based smartphone from Verizon—either the Palm Treo 650 or the Palm 700p [using either iSync or the Missing Sync for Palm OS]—or use the Palm OS-based Palm 700w with the Missing Sync for Windows Mobile as an alternative to the Motorola Q. That software will also support the Verizon Wireless VX6700, and presently supports the Samsung smartphone they offer.
The pre-release software for Windows Mobile 5 devices has limited utility, but you can read more about it here:
http://www.markspace.com/testing/MSWM25_alpha.html