I want to:

1. Receive an email, convert the header and body to an SMS message. Then Send the SMS message via my mobile/cell phone attached to the PC.

2. Receive an SMS on my mobile/cell phone attached to the PC, convert the text to email and then send the email to an address.

Effectively the PC will be acting as a mail server and the phone will be acting as an SMS gateway device.

At the moment I'm still in the thinking about it stage.
I don't have a distribution or mobile in mind, but I would probably want to develop and test the processing using my old Nokia 3210.

Anyone got any advice where to start?