Interfacing a micro-controller (PIC/SX28/etc) to Xbee

What is the right way of interfacing a 5vdc micro-controller to a 3.3vdc Xbee board?

I can imagine 4 ways:

1) Output of the micro-controller going directly to the serial pin of the xbee

2) Output of the micro-controller going thru a voltage divider circuit to the Xbee (anyone have the resistance values off hand for this?

3) Output of the micro-controller going to a transistor to switch the 3.3v to the Xbee (would this be fast enough to not cause interference?)

4) Output ofthe micro-controller going thru a 3.3vdc power regulating chip to the xbee (I know, this sounds like a really bad idea to me too...

I'm thinking either #3, or something I haven't thought of yet is probably the best idea, but I'm interested in hearing what you have to say...

Check with sparkfun. They have a level translator board just for the XBee. Look at their schematics.