Here you will find dozens of top sites that can help you track down common Windows problems.  Some sites are self-help, and others offer free support.

Free Solutions to Common Windows Problems
Windows Annoyances offers a very useful set of information on how to deal with common Windows problems. Nice set of tips too.  Highly recommended for all users except raw beginners.
http://www.annoyances.org/

Excellent Windows Resource Site
The About Windows Guide is among the best of the Windows portal sites. Tips, tricks, troubleshooting and more. Oriented to end-users rather than tech-heads.
http://windows.about.com/compute/windows/mbody.htm

Excellent Free Tech Support Sites
Subscriber Ted Green writes: "Thanks a million, Gizmo, for telling me about the Tek-Tips forums. With the help of the forum members I solved a Windows shutdown problem that was driving me nuts." Note, though, that Tek-Tips is geared toward experienced users. Beginners may get better results from the TechSupportGuy forums. Both are free and well worth trying.
http://www.tek-tips.com/
http://forums.techguy.org/

Free Computer Help
"Computer Hope" is an aptly-named web site offering useful online resources, a very active set of forums and a free email support service. I found the forums particularly responsive. Well worth trying next time you run into a PC problem.
http://www.computerhope.com/index.htm

Free Excel Help
If you've got an Excel problem you can't solve, try the busy forum at this site. It's free and the folks are very helpful.
http://www.mrexcel.com/board2/

Free Outlook Help
Some users just never get the hang of Microsoft Outlook. If you need help, check out this tutorial which is conveniently split into the various Outlook features.
http://office.tizag.com/outlookTutorial/

Fix for Corrupted Office Files
Got a user with a corrupted MS Office document?  Tried the built-in filter for raw text recovery and got nowhere?  Try this site, which has programs designed to help you.
http://www.officerecovery.com.

Database of File Extensions
Got a file with an unknown extension?  Need to know what created it?  This'll help.
http://filext.com/

Free Modem Help
Although not exhaustive by any means, there is still good information here for anyone looking for assistance with modems.
http://www.computerhope.com/help/modem.htm

Start-Up Applications Unplugged
It's frustrating trying to edit the Windows start-up list because the filenames themselves tell you little about the program's function. This free site lists thousands of common startup files, full descriptions of what they, and links back to the vendors' web sites. Top stuff.
http://www.pacs-portal.co.uk/startup_search.php

Download Missing DLLs
Most users have experienced a "missing DLL" error message. This site provides a free library of DLL files that you can download. http://www.dll-downloads.com/ See also this hand guide "How to fix a rundll error".
http://en.kioskea.net/faq/293-how-to-fix-a-rundll-error

Locate Spammers’ Real Locations
These folks provide a free online service which allows you to type in an IP or URL (web site address) and get the geographical location of the server. They also offer a variety of free tools to allow web sites to customize their web pages according to the geographical location of site visitors.
http://www.geobytes.com/FreeServices.htm

Disposable Email Addresses to Order
Need a temporary email address to give to some annoying web site that insists that you register? Well, simply make up anything and then add the suffix "@mailinator.com”. For example, giz@mailinator.com. Then go to the Mailinator website and collect any email to that account. It's free and you don't even need a password to get your temporary mail. All mail is deleted after a few hours.
http://www.mailinator.com

Troubleshooting Wireless Networks
Despite the advertising, I can assure you that installing a wireless network can be a real pain. If you run into trouble, try the excellent troubleshooting section at this site. The site has some excellent tutorials as well.
http://www.practicallynetworked.com/

Track Down Windows Errors
Thanks to subscriber David J. for letting me know about this site which allows you to track down solutions to problems in different Windows sub-systems. The organization of the site is odd but quite effective. It has about 400 topics arranged alphabetically. However, some of the topics are general, such as "Shutdown problems", while others are very specific, such as "sh31w32.dll." Once you select a topic, you'll be shown a variety of resources ranging from Microsoft Knowledge base links to simple fix-it guides. Overall, an excellent trouble-shooting resource. http://www.colba.net/~hlebo49/ 
This list of common Windows error codes and how to fix them is also useful. 
http://en.kioskea.net/faq/113-common-windows-error-codes-and-how-to-fix-them

How to Fix Your Printer Yourself
Sick of paying out big bucks to fix simple printer problems? Then try repairing it yourself using the resources provided at this specialist site.
http://www.fixyourownprinter.com

Sending Files Using The Internet
This article looks at three options for sending files, including large ones, over the internet.
http://www.techsupportalert.com/content/free-replacements-dropio.htm

HFS Personal Fileserver
For sending files of unlimited size you need your own mini-server. Install this tiny server app on your PC and give others your IP, then they can download any size of file whenever they like. You just need to keep your PC on till they've got the file. Definitely the best solution now for large files, though you're limited to the upload speed of your DSL connection (which is half the download speed). It just means a big file can take awhile but that hardly matters.
www.rejetto.com/hfs/?f=dl
Here is a good HFS tutorial

Great PDF Resource Site
If you are looking for Adobe PDF information or utilities, head straight for PDFZone.
http://www.pdfzone.com/

Beep Beeeeep  Beep
You turn on your PC and all it does is beep.  But what does the code mean? This site will translate for you.
http://www.pchell.com/hardware/beepcodes.html