Most people don't realize just how dangerous the internet can be, especially to Windows users. Everyone that is not a tech gets a computer virus sooner or later. The typical response is to discard the old computer or put it in the attic and buy a brand new one, an unnecessary waste of money. Where knowledge is lacking, the wallet must compensate.
To all users, I recommend the following. Use Firefox, and do not install any toolbars, but do install the addons AdBlock and NoScript. NoScript requires extra effort on the part of the end user, but the payoff in security is worth it. I do not install NoScript for clients unless specifically asked, because I appreciate the annoyance it can cause. For myself and loved ones, I will always install NoScript and train them how to work with it to have a safer browsing experience. Only scripts that have been specifically greenlighted by the user will be permitted to run. I also teach my users to be extremely skeptical of anything they read on a web site, in particular regarding their computer, but even beyond personal computer security, much of the information one finds on the internet is paid advertising or else people looking to "monetize" (the verb they choose) their web domain.
Also, backup an image of your Windows system to a separate hard drive--built-in Windows functionality available via the Control Panel--it only takes 20-60 gigs of space and will save your bacon in the event of operating system loss. I image my Windows systems every 3-4 months to capture any new program additions or removals. Be aware that backing up the system image is different than a complete backup. Microsoft does not make the differences quite clear to the user, but I discovered the differences through the time-honored method of trial and error. A system image backup captures the operating system and all files needed for Windows operation. A complete backup captures that as well as media files that may be stored on different drives. Everything should be backed up, but the system image is really important, because it allows very fast restoration of Windows in the event of a malware infection.
This is the best advice I can give to Windows users with my 30 years of experience, other than to consider giving Xubuntu a try for light duty such as Internet browsing. I use Xubuntu or SolydX on three different systems and consider it a worthwhile tool. It boots faster than Windows, is free, does not require much in the way of configuration, allows a high degree of customization, and requires very little in the way of system resources. Mine all run fine with 2 gigs of RAM in each box. The limitations of Linux have been described elsewhere on this blog.