Hey guys need some advice

just bought an audi A4 avant(2000 model)
comes with a rather naff tape player but have been told it should be easy
enough to get a cd changer for it

what would you reccomend to do ?

a) buy a cd changer to go with the system if so how much

b) buy an aftermarket h/u want something of equal or higher quality to the
standard system

ps how do i tell if its a bose system or not and what does this mean?

cheers

Rob