I want to take an Ethernet shield R3, and plug a proto shield on the top. The proto shield will have a Arduino Mini Pro 3.3v Atmel 328. I know I need a 5v and 3.3 v power supply. I think all I need to do is connect the D10-D13 pins to the Ethernet shield. But normally these pins would all operate on 5v, but in this setup, I've got 5v and 3.3 volts. So how should I deal with this? Any other pitfalls I should be aware of?
The reason I'm doing this is the Pro Mini is actually a panStamp - it's a Pro Mini with an RF transceiver built in.