How to secure Windows and remove any viruses and spyware

The only way to truly protect yourself is three fold: run protection to stop virus and spyware from running, block the sites that house spyware and prevent your apps from running spyware.
  1. Use a good virus scanner, the best you can buy is NOD32 ($39/yr) or Kaspersky ($49/yr). Even if you don't plan on buying it, use the 30 day trial to remove the spyware and/or viruses you currently.

    Download NOD32 here
    or
    Download Kaspersky here
    If you don't wish to purchase a good virus scanner, two decent free options are AVG and Avast.  Be warned that free AV solutions DO NOT have as good virus protection as a commercial package and give poor spyware protection, but free is better than nothing.
  2. Any good Anti Virus has built in anti spyware, but it won't hurt to assist it with a complimentary program such as Windows Defender which is a free Anti Spyware tool from Microsoft, which you need to add to XP, but it's built into Vista. On top of this, I would also run Spybot S&D because, it's not an active spyware preventer like Defender or your AV is, instead it's a manual process you run to scan your PC. The biggest reason I recommend it is that it's not maintained by a company, so there is no commercial interests or agenda.

    Windows Defender
    (XP only)
    and
    Spybot S&D
  3. Now that you have proper monitoring, it's time to prevent spyware and viruses from running from your Internet related apps. Following this 3 step guide which tells you how to install and use DropMyRights, which is a Microsoft program that will prevent spyware and viruses from running through IE, Firefox, AIM, IRC, Winamp, etc.

    Please note: Vista automatically runs IE in a protected mode, but you should still use this app on Firefox and other internet and audio apps to protect them too.
  4. Finally you should install HostsMan which will update your network HOSTS file and block any known spyware/virus sites. What this means is that known exploit sites well be blocked, so your computer can't access them. These are sites viruses report back to and/or use to re-infect your system.
    HostsMan
"Everything should be made as simple as possible, but not simpler." -- Albert Einstein