This article provides a list of the software packages that I use to either secure a PC or to fix a PC that's been infected by viruses, trojans, malware, and the like.
All the software on this list is free of charge, but often you can get an upgraded version for a few dollars, or donate some money to the author to help support the program.
For use with a laptop when traveling, or for use when people don't have a hardware firewall, I use ZoneAlarm from Zonelabs. I use ZA to protect the PC from intrusion — ZA can be configured to check your email, but I use a different program to screen for viruses.
For home installations I prefer hardware firewalls that also do NAT. I do not like D-Link or Belkin firewalls, the former because the "D" seems to stand for "Don't", and the latter because of what I consider egregious corporate misbehavior.
I use AntiVir. Antivir seesm to do a credible job of finding and cleaning viruses. AntiVir also has a "scheduler" built-in that lets you schedule when to run a scan of the disk automatically; twice a week is sufficient in my opinion. AntiVir also does a very credible job of downloading and installing updates automatically, also using a scheduler.
Antivir is what I recommend to defend against downloading virus emails, files, etc. Set it to load and run on startup. And make certain that you never have two antivirus programs running at the same time.
I recommend two packages, Lavasoft's AdAware, and Spybot. Both programs have their strengths and weaknesses, so it's best to use both of them from time to time.
The main defense against malware is to not load disreputable programs onto your computer; I don't have problems with malware on my machine (that I'm aware of). Spybot lets you "immunize" Internet Explorer against malicious software downloads.
For a browser, I recommend Mozilla. Among other things, Mozilla has exellent security features built-in, such as a setting that surpresses pop-up windows.
Mozilla does include an email program, but for business use I prefer to use a separate program for email. I use Eudora. Just as an example, a colleague of mine was being driven crazy by spam; I had him install Eudora, and its junk-mail filters immediately caught 99% of the spam.
One of the ways that viruses and malware take over your computer is through "startups," programs that run when you turn on your computer. For that matter, several otherwise well-behaved programs attempt to run at startup and put themselves into your PC's "tray." By running at startup the programs chew up memory and CPU on your computer, usually for no good reason (other than advertising the existence of the program). Very occassionally a program will attempt to register a one-time, post-install, post-bootup cleanup program. Startup control is a way of thwarting programs that attempt to register themselves to run at startup.
I use Mike Lin's StartupMonitor, which informs me when a program attempts to register itself to run at startup.
Startup Control Panel from the same author is even more useful: It lets me see what's already installed to run on startup. And I can turn things off (and on again afterwards) which is extremely useful when cleaning up a virus.
There's nothing quite like sitting down at someone's computer, running a virus scanner, and finding 78 copies of different viruses. Here's some of the tools I've used (aside from the anti-virus and anti-malware scanners) to clean up infected computers.
One note about cleanups: Some viruses are very, very nasty indeed. They erase copies of anti-virus software and try to prevent you from downloading new ones. They keep multpile copies of themselves running, and they change their names to make them harder to erase. A really persistent infection -- and many people have these -- requires that the computer be started in "safe" mode, which is done by following the instructions for your PC (often it's to use the F8 key on startup). In safe mode, nothing much loads on the computer, and you can then run the antivirus and anti-malware software. Sometimes this requires several cycles to catch all the problems.
Startup Control Panel, mentioned in the previous section, is a very useful tool to clean up malware problems, and of course to get useless junk out of the "startup tray."
HijackThis recently let me rescue a system that simply couldn't be cleaned any other way. HijackThis lists everything that attempts to intercept your web browser. This is not an analysis tool -- you have to decide for yourself if you think a particular item is dangerous or beneficial! Use with extreme care.
(Note: Here's a malware test. I had a firewall connected to the PC, but the firewall was not connected to the network. When I tried to use the browser on the PC to access the firewall, I would time out &mdash it took forever. It was because the browser was being hijacked, and the slowdown happened as the malware tried to get to the net, not realizing that I was only connected to the firewall's web page server and not the 'net. If you have these symptoms, you probably have malware. And HijackThis was the only way I was able to fix it.)
Dr. Delete is a tool to remove a file at next bootup. Good for getting rid of a file that simply seems to be stuck on your system.
lspfix is a tool that fixes the TCP/IP chain if it's been damaged by malware. I've never had to use it.
And as a nice way to get some junk off your system, CCleaner removes temp files from across the system. And yes, I think the program would be a lot more popular if the name were less indelicate.