How to keep your computer safe from viruses and spyware is a never-ending battle. It’s not possible to be 100% safe. However, there are steps you can take to reduce the possibility of inflection.

Purchase a good quality antivirus software package and keep your virus definitions up to date. Check out some reviews at http://www.antivirusware.com. It may help you with your purchasing decision. Some vendors have also free versions available. The free versions usually lack some of the features of the paid products. They provide basic protection, as long you keep the virus definitions up to date. I you have the budget, purchase the software.

Get a software firewall. Most antivirus vendors sell them as well, or bundle them with their antivirus software. ZoneAlarm Free Firewall is a popular free software firewall, you can download from:
http://www.zonealarm.com/security/en-us/anti-virus-spyware-free-download.htm

Keep your operating system and applications up to date.

On Windows XP

Select Start, Control Panel, Security Center, Automatic Updates

On Windows 7

Select Start, Control Panel, Windows Update

Other applications, like Acrobat Reader, Flashplayer or Java plugins also have regular updates. Don’t ignore them because they can be just as vulnerable as the operating system itself.

Do not open email attachments that look suspicious. Delete them.

Be vigilant, look out for unusual behavior of your computer. You may want to run a virus scan.

Change your passwords from time to time. Use passwords with a combination of  lower and uppercase letters, numbers and symbols.

Those steps should keep your computer reasonable safe from viruses and malware.