Cayenne buyer's advise?

[ChrisZang]

Hi,

I am looking for a used car for the wifey.
Looking somewhere in the ~ $25k range
Current candidates are:
a) 2006 ML350
b) 2005/6 E350 or E320
c) 2003/4 Cayenne S

Any owners of these cars out there with their opinions?
Also does anyone know if there is something I should look out for (meaning be worried about) when looking at a 2004 Cayenne S?

Thanks