Thank you SO much for all your advice guys. The problem with putting any anti virus software on a pendrive is that I don't know how to access the software from the infected PC which won't let me open any windows! I've eventually found the name of the malware which is System Check.Com and found a website Bleeping Computer.com which has insructions on how to remove the malware. Unfortuanley it tells me to :-
"Using the F8 Method:
1. Restart your computer.
2. When the machine first starts again it will generally list some equipment that is installed in your machine, amount of memory, hard drives installed etc. At this point you should gently tap the F8 key repeatedly until you are presented with a Windows XP Advanced Options menu.
3. Select the option for Safe Mode using the arrow keys.
I've tried to get it into the safe mode six times tonight and amount to wear out my F8 key, Windows XP still fires up with the maleware.
At this stage I would happily sacrifice my computer if it needs to be put out of it's misery but would love my photos and docs which at present I can't access to copy.
I think I need help from The Dr
I'll PM you tomorrow or over the weekend if your kind offer to help still stands as I'm a bit out of my depth here!