@Dianora Basically, it's just an old school trojan then. My advice, as a computer user since my age was in the single digits:

1. Backup often
2. Backup often
3. Practice safe computing, don't run things if you don't know where they came from and what they are supposed to do
4. If you can possibly avoid it, DON'T RUN MICROSOFT WINDOWS!
5. If you have to run Windows, avoid running as many of the more popular programs as possible. Programs like mIRC got attacked, other IRC clients ignored. Etc.