hi Kathryn:
There are several programs that are free to get rid of trojans.
Here is my best advice:
P.S. If your E-mail has attachments and you do not know the person DELETE that E-mail. better to loose an e-mail then your hard drive. Raymond.
Windows XP has a free firewall, but you must activate it to help protect your computer...here it is below:
Ad-Ware/Spyware protection
Always keep your microsoft updates, updated to help protect you from new viruses.
Good luck to you!
Raymond.