if you use the apparently excellent o2 broadband do you have to use it wireless or can it be wired. my mum is probably going to change to o2 but is very nervous about wireless security and has no need at all to be wireless
O2 broadband is no different from anyone else's. It's delivered to your house down the phone line.
What's probably worried your mum is the fact that O2 will give you a wireless router. But you don't have to use it wirelessly. As smackheadz has said, you can connect to it with a cable called an "Ethernet" cable, and switch off the wireless function if you want to.
I'm sure the router will come with full instructions.
I recently installed the o2 broadband router and it is very easy. It does almost everything for you and uses very easy language. Recommend it 100% and if you do have a problem their helpline is the best I have ever used.