Unfortunately, while the mouse is used for looking and attacking, the game uses WASDE, Tab, Ctrl, and the Spacebar as it's primary controls. It pretty much controls as an FPS, and the combat requires some fast response. I can't imagine how you could play it with only a mouse, I'm sorry to say.
However, given the examples you've posted, you might look into Divinity: Original Sin or Wasteland 2 for recent RPGs. They both play very similar to the original Fallouts and the Infinity Engine games and are quite excellent, from all reports (Wasteland 2 is largely produced by the original Fallout team, which may interest you). I can't speak as to whether or not they would run on your PC, since a lot of that has to do with system specs, but they both run on Vista, according to Steam. Wasteland 2 controls almost entirely with the mouse. I have barely played D:OS, but from what I recall that uses primarily mouse control as well.