I was able to pair my axim x51v with motorola H500. Here's my simple path to success.
1. I installed A2dp.zip (
http://www.aximusers.com/forum/bluetooth-ir/6922-
bluetooth-headphone-testers-required.html).
It did not work. Then
2. I installed new bluetooth drivers (BroadcomBluetoothStackx51Vo5.zip)
3. Soft reset. And everything works fine.
Thank you all.