I am using NT systems for several years and never saw or created any unknown account.
I suggest that you delete that one.. especialy if it is with admin priviledges...
you should consider visiting Windows Update, check your box for troyans and to install some personal firewall... Zone alarm is easyest to use...
you can find it many ways, but easiest is to go to www.download.com and search for it.. It could be on their top 10 list too...