from 16mhz to 8mhz

Will I lose any functionality if I put the chip on a board without a 16mhz crystal and program its fuses to run at 8mhz? Would I need to change my code? Will the serial functionality still work? What would happen if I put a chip set at 8mhz on a board with a 16mhz crystsal? Thanks,nik

please read this thread:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1163418637/2

you can even use the internal 1mhz oscillator:
http://wolfpaulus.com/journal/embedded/arduino3.html