I recommend the SERO plan with sprint. Private plan which includes 500 anytime minutes, unlimited GPS, unlimited night&weekends, unlimited texting, unlimited picture messaging, unlimited data transfer, for $30 a month.
Catch me on MSN or AIM, and I'll tell you how to get into the offer. Also, for a free $25 debit card once you join.
By the way, the phone I use is the Motorola Q9C. You can get a Mogul, or HTC Touch. All good phones, some features QWERTY keypad for texting, but all runs either Windows Mobile, Windows SmartPhone, or Windows PocketPC.