Can you use the blackberry pearl as a fax/modem? What i am trying to do is to send a fax from my PC using the balckberry pearl as the medium

No, not in the way I believe your talking about. Traditional (legacy) fax machines or fax modems require an analog phone line. If you can't send the fax from your PC with a standard DSL or cable connection, then you won't be able to do it with the Pearl.

If you have an efax account, you can send it via the internet through efax using the pearl as your internet connection.