Every time I open up a word or excel document, I'm getting a warning message that the programme is not a genuine copy - will anything happen to it at all?
I'd be fuc-ked if I lost my data - mind you all the data is on my back up hard disk, which is separate from the c drive where all the programmes and operating system are.
It only seems to heve happened since my last round of Windows XP updates, so if the worst came to the worst I might do a system restore to the previous point - the downside beiong I wouldn't be able to get any more updates if any bad stuff happened.

No it just means you wont be able to download updates for it.

Don't do that update shit. They count your money while you're asleep.

Go to Mininova and get the latest copy. It's not theft, you've already paid.