Tim,
I was under the impression that using #include <Ethernet.h> WAS the standard Ethernet library. Is that not the case? I have to plead ignorance unfortunately. I'm a proficient LabVIEW "programmer" but this Arduino code is not in my bag of tricks!
When I uploaded and tried the DhcpAddressPrinter I was having the same failed connection to the DHCP server...I'm also assuming that was using the standard Ethernet library.
There are no other SPI devices on the Arduino...no SD card in the slot.