John,
I just went through the same thing your looking into. I have a treo 755p with sprint, I had the $15.00 unlimited data plan. I found that when i tried to download the navigator software from the sprint site it would tell me that the software would not work on this phone. I went to the telenav site (
http://www.telenav.com/campaign/inde...4184sb13pi6ai1)
and checked, It said i could use the software.
I downloaded the software, installed it, and it works great. It does cost $10.00 per month w/unlimited usage. And you will need to pick up a receiver. I then went to the sprint store and asked them to sign me up for the $25.00 plan which includes the unlimited navigator, and TV and all the extras. So for the extra $10.00 per month it will work great.
Hope this helps
Ron