I am looking for an unlocked GSM Treo device. I understand that my only option from the Treo store is the 680, which is Palm based. I would rather have a Windows based system. I notice that there are a ton of unlocked GSM 750 devices. What is the story with those devices? I don't want to jeopardize the warranty by buying a unit from a second hand reseller. Thanks in advice for your help.