Dear friend,
U r using Windows, right?
Do this,
1.Do updates always
2.Find a nice Antivirus.... Go to www.grisoft.com , you can find one free Poweful AV...
3. Install a FIREWALL... Go for ZONE ALARM or SYGATE.. Everything is free.
Please do not open files with extensions .PIF, .EXE, .SCR etc... These days, you can see them as ZIP files too.. Well well, usually these ZIP file size is 20 to 40 KB... Take care while opening ZIP files in that Size, Make sure that it is something what you are expecting, Otherwise delete them straight away... Sometimes HOTMAIL , Sorry, Mccafee Will tell you that ATTACHMENT is virus free... Hoooooooooo, damn, you are trapped.... So, take care man... Try using Linux, You will link it..
Manu