All I know is what the ad says
"Processes
Stick (SMAW)
DC TIG (DC GTAW)
Air Plasma Cutting and Gouging (PAC) with Optional Spectrum Models
6,500 Peak Watt AC Generator"
That may be refering to its ability to carbon arc cut / gouge, which still requires a seperate air compressor and is significantly differnt from plasma cutting. I could be totally wrong though.
As far as a gas powered welder, like others have said, the Miller Bobcats and Lincoln Rangers are very common and should be easy to find parts for. The next step up in size is a Miller Trailblazer / Big 40 or a Lincoln Vantage. Those are very spendy. All of these machines have welding output as well as regular 120V/240V output for running tools or can double as a back-up generator in a pinch.
Unless you're burning a lot of rod, I'd steer clear of a SA-200. They are great for what they are as tpierce said, but they are not very versitile. You would be much happier with a Bobcat or Ranger.
As others have said, if you already have a welder, you can get a regular generator and run it that way. I have run both a Lincoln Precision TIG 185 and a Miller Dynasty 200 off a 13,500 watt Northern Tool brand generator before with great success. The Dynasty will run of a standard 15 Amp circuit... but we already had the big generator.