Just to summarize some of the things I have discussed on the topic of how not to get fired over internet use, I believe that if you follow all the tips I have provided here as well as do some research into your own company and how much lenience your company provides on the work computer, will allow you to keep the job that you have.

Good luck!

More interesting stats

According to a blog on this same topic here I found some interesting statistics about personal use of work computers.

• 45% send personal e-mail

• 33% read the daily news
• 31% gather local information
• 31% investigate travel arrangements                         
• 24% visit sites related to hobbies
• 24% participate in contests and sweepstakes. 

This shows that people are doing a lot of things that is not necessary or specific to the job that they must get done. It makes sense that employers and companies jump into action when they see such high numbers of "time wasting" on the job. Things like this will not help the productivity go the employee and therefore the employer and or company must take action. 

Do's and Dont's

Do's

• Make sure you learn your company's rules and policies:Doing this will allow you to learn what you can and cannot do on your work computer.
• Attempt to minimize sending personal e-mails from work: If your employer or company does not allow you to do this, them simply don't, or keep it minimal.
• Be careful when using social networks: When you are using social networks at home or at work, ensure you do not talk about the company that you work with. All of these websites are easily accessible to anyone so your employers can see anything you post, in saying that be careful. 

Don'ts

•  Do not keep anything that could insult or is frowned upon by the company. For example don't send or download pornography, sexually explicit jokes or inappropriate backgrounds.
• Do not open any attachments send via e-mail from someone you don't know. These attachments could carry viruses, spyware, or anything else that could jeopardize the security within the company
• Don't use your companies computers for your pleasure. Meaning don't store music and stream videos from the companies computer.

Learn The Rules

Every company has its own rules for internet use on work computers, So simply learn the rules that your company has provided. Some companies will not allow you to send any personal e-mails from a work computer, and many people do. If you are unaware of rules like this you may be jeopardizing your job.
Stay informed to avoid being laid off.

Pornography

Well as this might seem like a useless topic since no one should do this at work some people do.
be sure not to send, download, or watch pornography at work. Also along the same lines make sure you do not have inappropriate screen savers. This may seem like common sense but it does occur.

Public or Private?

When sending e-mails at work try your best to keep them related to the job you need to get done. The more personal the e-mail the higher risk you are at losing your job. Employers can monitor everything you send as I have stated many times before, so if you keep all your personal messages on your personal computer at home. When at work focus on the job you have to get done.