Mark's Blog : The Case of the Slooooow System
http://blogs.technet.com/markrussinovich/archive/2008/09/24/3126858.aspx

The Case of the Slooooow System

Tips for the Mac!

The boot process on a Mac is a magical process, all you see is a grey screen with the magic happening in the background. Did you know that very are various keys which you can use to change how you Mac boots and access certain settings. They are not for every day use, mostly troubleshooting. They are worth knowing if anything goes wrong.

How To Diagnose a Suddenly Slow Windows Computer? -- article related to Ask Slashdot, Windows, and IT.

stackoverflow, but for sysadmin

A system administration Q&A community created by the same guy as Stack Overflow (Jeff Atwood).

Social site for Sys Admins to ask questions

Server Fault is a collaboratively edited question and answer site for system administrators and IT professionals – regardless of platform. It's 100% free, no registration required.

MaximumPC.com is the best online resource for PC Features. Visit Maximum PC and read about Blue Screen of Death Survival Guide: Every Error Explained.

HOW TO Troubleshoot a Flaky internet connection

This page offers links to flowcharts for PC diagnostics, excerpted from my book. The non-active links are for charts that are included in the book but not available online. The published book contains seventeen flowcharts for computer diagnostics plus a short text for every chart expanding on the decision points. The troubleshooting process is the same for an expensive Sony or IBM, or a downmarket eMachines or Gateway. Dell and HP (who purchased Compaq) manufacture PC's in a wide range of price points, but you have to go through the same troubleshooting steps for the cheap ones as the expensive ones if you want to correctly identify and repair the failure.

Diagramas de flujo para diagnosis de problemas de ordenador

http://www.fonerbooks.com/pcrepair.htm

Today marks a big change at MacFixIt. All articles are now available free-of-charge, allowing anyone to access the most timely, comprehensive and unbiased library of Mac-related repair and troubleshooting advice available online. This is a milestone in the history of MacFixIt. This change is a direct result of our acquisition by CNET and allows us to provide a broader range of coverage, in addition to drawing on a new pool of knowledge and resources. We will continue to provide timely and relevant reporting of Mac-related hardware and software issues and will be adding new features we're sure you'll enjoy and appreciate.

http://www.lookinmypc.com/

Little Registry Cleaner is an open source program designed for Microsoft's Windows Registry. Its purpose is to remove obsolete or unwanted items that build up in the registry over time in order to improve the stability and performance of your computer.

Msoft fix it center from Gizmo

Hmmm

How To Diagnose a Suddenly Slow Windows Computer? -- article related to Ask Slashdot, Windows, and IT.

Interesting, most of the comments are related to a soon to fail HD (with suggestions to test it)

Computers are easier to use and more dependable with each new generation of hardware and operating system update, but that doesn't mean they're problem-free. Here's a look at the five most popular tools for troubleshooting your computer problems. Earlier this week we asked you to share your favorite diagnostic tool. Below, we've rounded up the top five answers, and now we're back to highlight the most popular computer diagnostic tools among Lifehacker readers.

from Lifehacker

Soluto Is an Awesome Tool to Speed Up Your System Boot & Fix System Slowdowns http://j.mp/bZiE3A

Looks interesting, but comments reveal many problems.

Windows only: Soluto bills itself as an "Anti-Frustration Software", and it's not hard to see why—it tracks all the applications in your system boot process, and tells you exactly which ones are slowing you down.