Two things worth noting, regarding previous comments:
Dossy – you mentioned having a Samsung i330, and that you’d never touch another PalmOS device again. You should realize that the i330 runs PalmOS 3.5.3, an extremely old version of the OS (roughly the same version loaded on the old Handspring Visor models. Since it was built for PalmOS 3, the system specs were designed accordingly. The Treo 650, by comparison, is a modern PalmOS device, running the most current version of the PalmOS, and with customizations designed to improve the user experience. What’s more, the Treo 600/650 has a thumbboard, rather than relying on handwriting recognition for text input, and is roughly the same size as a standard candy-bar style cell phone. You’d do well to give the Treo a shot.
Also, there’s a verison of Missing Sync for PalmOS that not only replaces the Palm desktop application, but improves upon it in many ways. I believe the website is markspace dot com. While Missing Sync does not USE iSync, it will sync to all of the standard Mac applications (address book, ical, etc.).