Securing Windows XP - simplified
Securing Windows XP is easy. You just need to follow a few hundred easy steps 
Seriously, I’ll try shortening this up. First, you need a *good* firewall. I don’t know about you, but I just don’t trust the built-in one. Don’t know anyone who knows what it is and trusts it, though…
The best firewall I’ve come to use is Comodo Firewall - it has a period of learning, let it know which apps are safe, you will be the mentor for a while - but it’s worth it. It’s rock solid.
Next thing in the list - windows update. Set it to Automatic (Click on Start - > Run - type services.msc - press Enter - find Automatic updates, doubleclick on the service, set it to Automatic and start it. Remember this site, bookmark it and visit it regularly to check for new updates - http://www.update.microsoft.com/microsoftupdate/v6/default.aspx?ln=en-us
Number 3: Security policy. You could do it automatically by downloading pre-configured security policies from NSA and follow the documentation, or if you prefer to know what you’re doing, and you are not in a domain network, click on Start, Run, type gpedit.msc, Enter. You will be presented with a tree view of settings, just go through them and set them to your preference.
gpedit.msc
I strongly suggest reading the documentation in the above NSA link, though.
Number 4: Users. Install your apps as Administrator, and create a regular user for everyday use.
Remove their membership from Users group, and make them members of Guests group.
Log in as Administrator only when needed to install or remove something. Why? Just do it, don’t ask questions. Set passwords for all users you create, including Administrator! How to create users? Click on Start, Run, type lusrmgr.msc (sounds crappy, I know, MS makes joke of us), press Enter,
users
Click on Users - right-click on Administrator - set password - and set a password for your admin account. Right click on Users, create the users you will be working daily with.
Number 5: Never, EVER download any cracks, game patches, online video players, screensavers, etc, just don’t because most of them are infected by viruses, spyware, malware or trojans. Think about it: who will ever spend time and money to create a crack, website, free screensaver, and give them to you for FREE, if the program is not opensourced? No free beer out there. YOU GONNA PAY BASTARD!
Number 6: This guide is short and helps secure your home pc to some acceptable level. You could check out the link I posted above with the NSA security configuration guide - if you really need deeper level of security for your XP box, implement it step-by-step.
Good luck!