Thanks for the response.
Yes, it's a home usage machine. It's not on a LAN, it's connected to the internet with sn Ethernet cable froma Belkin router, which also has a wifi of which we run 3 or 4 other machines.
It's running on XP, and I only use Mozilla Firefox, Outlook Express, IE7, and the MS Office stuff on it. AVG Anti Virus Free.
I'm going to go through the stuff on that link and see where we go from there. I'm mainly concerned that security may be compromised as I use the machine for banking and so on.