I have an ipaq rx115 or something,windows mobile, 3000mhz processor, bluetooth, wifi, blablah, before that i had a good old palm V and believe me the palm os gets things done, the windows mobile crashes, the interface sucks, is by far less responsive, 'graffitti'-like input is a joke, etc. so i'm going back to palmOS and a treo 650 sacrificing some functionality but having a SOLID os and gui versus bells and whistles and no substance, great choice you'll love it
and DON'T upgrade to the windows mobile treo 670, it will suck major penis. i don't think i could use my current windows mobile pda as a phone ever, let a lone a contact manager or scheduler.