Originally I learned on the SusE 7.x releases. While I liked their tools, I opted to move to Slackware because the configuration files didn't rely on a specific tool to alter the daemon's configuration. While I still use Slackware for firewalls and systems with limited resources, I eventually moved to Gentoo. Gentoo offered a nice learning curve with the idea of 'Build it like you want it'. This was appealing and I generally use Gentoo as my desktop linux and a few server implementations. Their documentation can't be beat either. Though I knew of Debian and their claim to stability, I never gave them a chance until mid-2006. I have to say that I love Debian and the apt* tools. I really should have given Debian the chance they deserved a long time ago. Debain is an excellent distro for server usage.

Sample IPtables firewall
Guide to configuring Grub
Kernel Compile Guide
Using the path command
Information on customizing your linux prompt
Guide for the NetGear WG511 wireless card

Windows -> Linux Application list
Linux Kill Signals
Simple Kernel Compile Guide