DHCP was faulty in version 1.0 of the IDE, without a patch it would freezing during the DHCP request. This should be fixed in 1.0.1. Have you tried your sketch with the new IDE already?
It is possible but you have to change the board connections, disrupting the connection between the reset pin of the ATmega and the reset pin of the Wiz chip. Then you have to solder a connection from the reset pin of the Wiz chip to one of the digital outputs of the ATmega and you have to reset the Ethernet yourself after power up. I recommend against that because it's not solving your problem but giving you the chance of a few more.