Hi Jim- this is something I've been trying to acheive reliably for some time, with little success.
I used to use Rudeo Remote but it is not compatible with Vista, and seems to have stopped being developed. It was far and away the best I tried.
Recently, Salling Clicker was updated, but I couldn't get it to work in my system.
There are a lot of apps out there, but most either need WinAmp as the front end, or only work over BT.
You may want to look at
This article by Menneissys