Question: I recently reinstalled the OS (Windows XP Home) on a friend's heavily spyware/adware infected machine. It appears as though his kids (7 and 11 years I believe) were visiting sites that offered downloads for search bars, screensavers, and "cute" cartoony animations that anyone with safety in mind would never download.

Some of the concerns I noted on the machine were:

* The main account was Administrator
* Expired anti-virus software
* Lack of Windows updates
* Multiple firewalls installed

Basically, I'm looking for a guide for non tech-savvy users that would help them avoid getting infected again.

Answer: 
If the question is really to help them avoid getting infected again, and it is a computer for the kids, I recommend you to do some research on deploying [Windows SteadyState](http://www.microsoft.com/windows/products/winfamily/sharedaccess/default.mspx) for that particular computer.
One of my standard answers to this kind of question is to use [OpenDNS](http://en.wikipedia.org/wiki/OpenDNS), because it allows users to block sites that are known to host malicious software from the router so that it keeps all connected PCs clean.

If they're the kind of users who won't renew [AV software](http://en.wikipedia.org/wiki/Antivirus_software) for expense reasons they are better off with a current free AV solution than an out-of-date commercial one.