You have just installed Windows on your new PC. You take a broadband connection and connect to internet. How much time do you think you have before it gets affected by viruses, worms and spyware? It can be as less as 10 minutes.
Hence I always advise the first thing to do when you connect to internet is to first make the computer secure enough for general browsing. Just 2 small steps should be sufficient for most home users. First, install Mozilla Firefox. Second, install an antivirus.
Why use Firefox? Cause IE is insecure. Because you think you have been just surfing the web and nothing else, and you will never know when a spyware hit you (especially true if you do not have SP2 on your Windows XP) . Take my advice, install firefox and forget about IE. You will never need it again anyways.
Now for antivirus. Typically, home users do not install antivirus because the only 2 antivirus software they have ever heard of and have faith on are Norton and McAfee are too expensive to buy for a home computer (or too much effort to get pirated copies). Or because it slows down the computer. To overcome all these issues, go for freely available antiviruses such as AVG Antivirus Free Edition. It works pretty good for home users and takes less resources than commercial antiviruses. I have been using it for quite some time and am pretty satisfied with the results. Another alternative is Avast Home Edition, which is also quite popular and free but has a limitation of registering and re-registering every year (free of course).
The next steps to take would be to install an anti-spyware and a firewall. I'll take those up in the next post.