Hi
It is possible that something malicious could have been downloaded silently.
If you are worried, you could start here
http://www.techsupportforum.com/secu...ml#post1771806
Do not post your logs back in this thread - follow the guidance in the above link!
Please note that the Security Forum is always busy, so I would ask for your patience while waiting for a reply - it may take a few days.
If you want to go down the other route, i.e. wipe the hard disk and start again, then I would certainly recommend re-installing Windows. Malware can hide in many places, including Windows system files. A good utility to completely wipe a hard disk can be found here
http://www.dban.org/
If you are unsure about anything regarding the wipe and re-install post in the XP Forum.