Anybody know where I can buy speakers for a jaguar x type that actually fit?

I wanted to replace my speakers in my jag cause one of them is blown and the others don't sound so hot when its turned up past a certain level. Anybody know the size or where I can go to look? I live no where close to town so I'm guessing I'll order them online if I can. Thanks in advance.

Additional Details: 2002 Jaguar X Type, 4-door Sedan, no premium sound just what was put in from the factory. The speaker that doesn't work is in the front passenger door.