Selecting Timer Functions
Jan 2002 - Robert Dunlop
An explanation of the available timer functions and a comparison to find out which one is better.
Timing and FPS
August, 2001 - Andreas Jönsson
Shows how to animate graphics using the timing function instead of locking the framerate, and how to calculate frames per second.
Performance Counter Value May Unexpectedly Leap Forward
This MSDN article mentions a problem with the performance counter where it may jump several seconds, it also shows how it can be countered.
Game Physics: Fix Your Timestep
Glenn "Gaffer" Fiedler
This article gives a good idea on how you should do to keep the physics stable, while still allowing variable frame rates.