Your copy of XP was not patched, and you didn't install a firewall so you will find that a stock XP will be infected within a few minutes of connecting to the internet.
Read http://support.gateway.com/s/issues/2-976684501.shtml and note there are many versions of this article.
In closing, you should order the SP2 CD so you don't have to download it.
I bought my machine a year ago, and because of no phone line have not been on the internet. A nearby neighbor let me move my machine into his oversized computer room. I plugged into his computer line and I can dial-up and connect ok, but within 1-2 minutes I get a message box that says this system is being shut down by NT Authority and says to save all material and a clock is counting down from 60 seconds. It also makes reference to an lsass.exe file. The file extension says that it is in located in Windows\System32\lsass.exe, but when I do a search of my C drive it says that there is no such file. Even using task manager I can't stop this process. The only way to interrupt is to unplug and reboot which I end up having to reboot any way. The other computers are connecting to the internet ok. It just seems to be a problem on my machine. Any help out there.