When it won't work

Anand Tech Reviews, analyses, hardware news.
Annoyances The name says it. Discussion of various annoying features of OSes and applications and work-arounds.
Arstechnica Lots of primers
Black Viper Installation guides, PC tips, buying advice, reviews.
Brian Livingston Brian has written many good books that help people with their problems with Microsoft Windows.
Process Library Explains what all those tasks are that you see in Task Manager.

Building a PC

Hardcoreware Guide to making a dead quiet PC
My Super PC Lots of step-by-step instructions
PC Mechanic Another step-by-step guide
Tom's Hardware The latest hardware news, especially about processors.

Drivers and Patches

Windows Update Access the Microsoft list of updates and patches
The Driver Guide Device drivers for various hardware items.