My stock speakers rattled because the screws were loose. You may want to check that out for a cheap fix.
Most aftermarket head units all put out about the same amount of power, 18-25w rms, with the difference between any of them not too noticable for pure loudness.
The stereo was the first thing to go on my Contour. It was just unacceptable. I used the stock spaeakers with in my setup for about 8 months and was impressed overall for the money I spent. You can do quite a bit to help the sound quality for only a little amount of money.
Set up a plan for what you want to end up with, even if you cannot afford the best or all of it now.
Aaron
