fbsdmd,
Turn up the radio? HAHAHA. That's the best reply I've read all day. It's funny, because it's true.
SLW, I hear a rattling/knocking noise when starting my car although I don't remember hearing it when I bought it brand new, but the noises appeared soon (within the first 5 to 10,000 miles of driving). Also, not sure if this helps but the noise seems to have lessened after bringing it in for my 5,000 service.
As I type this my car is at the dealership getting a 15,000 mile service.
*Edit
I should add that like the other replies on this post, the noise seems to go away after driving around for a while.