Plea for technical help

*Warning: Dull post. Do not read if you came here to be interested or amused.*

I am aware that I ask for technical help (usually on Twitter) several times a day, but I am taking a liberty and doing so once more.

This time it is not for me and my blessed Mac, but for a family member’s PC computer which I am attempting to make work this weekend. If I can do so I will get superb numbers of brownie points and will generally be regarded as some kind of hero.

Here is a summary:

Problem: Can’t surf the internet / do e-mail.

Details:

• Computer is a quite old Evesham one running Windows XP
• Modem appears to connect to the internet, but no data is actually received.
• On the modem (Voyager 105) Power and DSL lights are on, Data light isn’t.
• ISP is Supanet if that is of any relevance. They say the connection should be working. They also cost 50p a minute to chat to.
• It worked until a few weeks ago, then stopped. Unfortunately I wasn’t here at the time, so I don’t know whether anything odd was done to it.
• AVG free is running, as is Windows Firewall. Disabling either or both makes no difference.

So, what I’m wondering is (a) any thoughts what the problem might be? (b) how would I go about making a diagnosis and, all being well, fixing it?

Normally I’d do copious Googling, but I’m connecting via a dongle on a netbook and too much internetting is a bit awkward.

Thanks in advance for any help you can give.