and if you had been using your aircon,it wouldve been making a hell of a racket,mine went the same way and the noise was bloody terrible. as nik has said,but on investigating your spline on your compressor if it is ok and intact,then you could try sourcing a compressor from ebay cheaply and rob the clutch off of it, this is what i ended up doing,i posted my findings of repairing it on here so do a search on it, as for driving without your under tray,BEST NOT.as the power steering is located at the bottom somewhere when you hit a puddle it can affect the steering,common problem. again do a search on this for info.