Are there any PDA/Smartphone type devices out for Virgin Mobile? I am looking for a windows mobile device if one exists, but have not seemed to have had any luck.

If there are none available, does anybody know if a phone from Sprint or Verizon can be flashed to work with Virgin? And as a last resort, can I use a Virgin Mobile Canada phone (Blackberry or the such) on a US Virgin Mobile plan?

Any advice would be appreciated. I am trying to find a decent prepaid plan with unlimited voice and data...having little to no results.