plugging arduino mini (3.3v 8mhz) into usb?

my arduino mini just came in the mail but i realized i probably should have ordered a usb serial adapter.....

is there any way i can plug it into my computer without wasting more money on a arduino mini usb adapter that ill never use again?

i have an arduino mega i thought maybe i could programming THROUGH the arduino seeing as its got all the requirments i need and id just need it to tap into the tx/rx lines that the usb serial adapter already uses and everything i upload to it would in turn get into the arduino mini.

i wanted to ask because im sure someones already built some kind of code like this.

also i just ordered two xbee adapters and they dont fit into my breadboard! anyone have similar issues? they dont seem to slot nicely with anything.....