Other 'Bad Stuff'
You would think that virus and spyware is the worst stuff. You would be wrong. There are some really ugly programs called keyloggers. Some people consider keyloggers to be spyware, and in a sense they are, but they can do far more damage than most spyware programs. A keylogger captures every keystroke the user makes. This includes usernames and passwords for web email sites and financial sites! Just imagine what damage that could cause! A confidential email could be read by whoever has installed the keylogger. The majority of spyware remover programs will not find a keylogger!
And there are Trojans! (pretty much a combination of virus, worms, spyware, you name it!)
If a computer is not protected by a firewall it can be attacked in a matter of minutes by some virus, notably the MSBlast and the Sasser worm.
Then there are the hackers. A hacker can just about destroy a computer and the computer owner as well if confidential and financial data is stored on the computer. There is so much written about hackers and the damage they can do! The following site has a lot of information that is well worth taking the time to read what the site offers. PBS.org.
There are several free firewalls available for home users. Windows XP comes with a firewall that will keep hackers out, but unless SP 2 has been installed, the user has to turn the firewall on as it is not on by default. The Windows firewall will not alert a user if a spyware is trying to 'call home'. Third party firewalls such as Zone Alarm will let a user know what is trying to 'call out'.
Probably the worst things that currently targeting unsuspecting computer users are the 'phishers' (pronounced fishers). This is a scam that uses email to lure victims into providing thieves the information needed to steal the victims' usernames and passwords to their financial sites. This could be a bank, PayPal, eBay, credit card or any other site that involves money.
Every day a new and insidious ploy is unleashed on unsuspecting computer users.
With all of the stuff that can happen with virus, spyware and other nasties on a computer, one of the big side effects is the computer gets so bogged down with all of the malware running in the background that the computer becomes totally unusable. This is because everything is loaded into the computer's Startup and all of the resources are used by the malware.
Unfortunately there are no programs that will protect users from themselves. There are countless warnings out there that tell users not to go to suspect sites, not to open emails from folks they don't know, not to click on links in emails from suspect emails, not to open attachments unless they are expecting the attachment and never ever buy a product from a spam email. In spite of all these warnings that are in user groups and even on the media (TV, radio, magazines and newspapers), users are not following advice and are being bombarded by virus, spyware and hackers everyday. The only protection is education. Responsible computer users are educated!