Ive just gone from an n80 to the n73. I have used the settings wizard to setup my o2 connection details but the phone will not connect to the internet. I have installed emsn and that wont connect either. Seems to send texts ok though.
The n73 is a sim free model with generic software and my sim card is O2 Pay and Talk. I never had any problems with connecting with the n80 and the same sim.
If not, that could be the answer. I had the same problems with my sim free 6670 on Vodafone. If you're trying to go through the O2 service, it may not allow it because most operators have something hard coded into their handsets. I couldn't even connect to Live.