there are several different types of programs that people call virus

• Trojans
  don't  replicate or copy itself, but does damage or compromises the security of the computer.  it relies on someone emailing it to you, it does not email itself, it may arrive in the form of a joke program or software of some sort. 
• Virus
  program or code that copies itself , it infects another program, boot sector, partition sector or document that supports macros by inserting itself or attaching itself to that medium. Most viruses just replicate, a lot also do damage.
• Worm
  a program that makes copies of itself,  from one disk drive to another, or by copying itself using email or some other electronic communication. It may do damage and compromise the security of the computer. It may arrive in the form of a joke program or software of some sort

excellent online virus checking site:) free too :) http://www.housecall.antivirus.com/ its a great tool to use in conjunction with your onboard antivirus    also check www.bitdefender.com   or  www.commandondemand.com

why you don't just click any link you happen upon on the net............ click here

a tip : if you use outlook> make an address book entry with the name !!!!0000    or such.... and enter no details. if you happen to get infected, this should stop it from auto sending to those in your address book. ( how? it will be the first entry in address book, and will trigger an alert of no email address found.... worst case? the virus sends, but you at least know.... )

a good idea is to also disable windows scripting... personally i open up windows explorer, click view, then folder options, and on view tab unclick the remember how files are opened options. you will get a pop up when you want to open some files, but its worth it.... also go to .. control panel - windows tab - accessories (double click) and then uncheck vbs scripting.
for more on disabling .vbs....... check here or here :)

• do not send, click, open, save, or run exe email attachments.
•  even trusted sources may be infected with  worms and viruses and send them to you !!! The best policy is never to send or receive executable attachments by email. 
• If you must send or receive email attachments, please make sure all of the following are true:
• Know what you are sending  via email (don't victimize others for the sake of a funny program or document, and don't desensitize your friends from being cautious by sending frivolous executable attachments).
• Know who the e-mail attachment is from before you click, save, or run it.
• Be sure that you were expecting the attachment from a known and trusted user .
• Have current anti-virus software installed on your computer~ update it update it update it!
• Have important documents on your computer backed up. If you are not backing up, get a zip drive and make regular backups of your data files (not your program files which are already backed up on original manufacturer installation disks). burning to cd will work too.
• If you have any doubt  >>> delete suspicious email messages/ attachments and send email to the sender telling them that you suspect a virus.