Windows Freeware Apps You Need

You know, the internet has a lot to offer, but all too often what it offers are problems for your computer. Virii, spyware and other malware run rampant, and you need something that will help. All of these are 100% free and will help protect your PC better than some commercial applications, and far better than nothing at all.

AntiVirus
Avast - Nice freeware app and one of the better free antivirus programs. The pre-boot Windows scanning agent is especially nice when it comes to ridding your PC of some of the more stubborn virii. You must register (for free) every 14 months.
Avira - The first free antivirus that I ever used is also quite competent. It's not quite as full-featured as Avast and pops up the occasional add for its full version, but it gets the job done for the most part, and isn't as resource-hungry.
AVG Anti-Virus - I've never really used this one, but it's generally the most widely-used of the free apps.

Anti-Malware
Spybot: Search & Destroy - One of the better anti-malware apps available, and it's totally free. This will basically scan your PC for a plethora of spyware (over 60,000 known variants), clean your PC, and in 17,000 cases, actually immunize your PC from infection. Install this, keep it updated, scan often.
Lavasoft Ad-Aware - Another great anti-malware app, Ad-Aware targets a slightly different type of malware than does Spybot, so it's good to use these in tandem. If you're getting lots of random pop-up ads, this one is particularly useful.
Windows Defender - Normally I wouldn't recommend a Microsoft product in a thread about security, but this does the job and it's free (if you have Genuine, aka, NON-PIRATED, Windows). I liked it a lot better when it was Giant Antispyware, but it still meets the criteria and gives some options the others don't.
AVG Anti-Spyware - I tried this one and didn't like it much (doesn't self-update), but I work with folks in IT who swear by it, so I'm including it due to their word alone.
AVG Anti-Rootkit Free - Rootkits are basically nasty little apps the conceal potentially harmful processes running on your PC. These have been pushed out by the usual ne'er-do-wells that usually make life miserable for the average PC user, as well as corporations like Sony in an iron-fisted attempt to enforce DRM. Use this if you need none of that nonsense.

Browsers
Mozilla Firefox - Firefox has basically become the alternative browser of choice for this generation of computer users, and for good reason. It's fast, stable, and not as susceptible to malware as Internet Explorer. In addition, it adds truly user-friendly features like tabbed-browsing (now incorporated by Microsoft in IE7) and extensions, useful, user-created tools that will help you do everything from check the weather to download embedded videos.
Opera - Another great browser (same as found on the Nintendo Wii...heh). This is one of the fastest full-featured browsers for Windows and can scream through pages. It has a nice look to it, and like Firefox (probably even moreso), it's not as susceptible as IE.
Mozilla Seamonkey - Another Mozilla-based browser, Seamonkey is what the Mozilla Suite has become. If you like one program to handle your browsing, e-mail, IRC & HTML-editing needs, this is it. Includes support for extensions as well, and has what I consider to be the single coolest name for a browser.

Other
Mozilla Thunderbird - The only e-mail client you'll ever need. Fast and efficient, with support for extensions, Thunderbird is probably the most configurable e-mail client available.
Open Office - You need access to Word or Excel, but don't want to pay $300+? Open Office is what you need. Free for download, it includes apps that do exactly what Office does, including save to Microsoft's file formats. This will be one of the best chunks of change you ever saved.
Foxit Reader - Adobe Acrobat Reader is slow, clunky, and, when using the browser plugins, crashes both IE & Firefox on occasion. Foxit is fast, small (less than 2MB) and generally much less of a hassle. Foxit also offers a PDF creator, but it will leave a watermark on your created PDF's unless you pony up $99.