Installing Android ADT/SDK on WinXP/Vista/Win7 (Step by Step)

Here some useful tutorials I've found Setting Up An Android App Build Environment With Eclipse, Android SDK:

Tutorial 1 (Android.com - All Operating Systems)

Tutorial 2 (HowToForge.com - Ubuntu)

Tutorial 3 (If-Not-True-Then-False.com - Fedora 16/15, CentOS/RHEL 6)