CPU is the only way to go. I run my radar and GPS off of it. I would recomend spending a little money and getting the software from nobletech. You can run into problems and they help in any way possible. DGPS ~ $250. CPU go to dellauctions.com ~ $500 includes a warranty plus it is pretty fun. Nobletech software can vary depending on what version you buy ~ $250 - ~ $750. I have run Garmin, Furuno, and an Echotech and this setup is by far the best.

When I interfaced the radar it even made it better. I can place boats up to ~5 miles away and see where they are at in relation to the chart. It is a thing of beauty.