I just came across this promotion on the nokia website.
Download Fifa 08 on your phone (via N-Gage) or on your computer and install it on your phone.
Type your mobile number in on the Nokia site and they will text you a free activation code for the full game and not a trial demo.
Saving you £5 - £6
I just did it on my N95 8gb and the game is great! very addictive!