PhoneControl is OK. I messed around with it for a while (UMPC mounted on my dash), but it is a little laggy over bluetooth. In the end, it just wasn't a very satisfying experience so I ditched it. Now I'm just using my phone to receive phone calls....go figure
It was an idea that seemed cool, but in reality wasn't particularly practical for me. One reason being that it is way too loud inside my S2000 to use the car speakers and computer mic. Might work out for you though. I'm sure a 745 is quite a bit quieter inside
Edit: Looks like PhoneControl is no longer being developed:
http://phoco.net/content.aspx?id=home
Probably still copies floating around if you want to try and find one. Maybe there is a better program out there. If you do find something that works great over BT, post a link please.