http://opensecuritytraining.info/IntroX86.html
Assumes: basic knowledge of C
Teaches: x86 32 bit assembly, registers, and stack usage. Uses MS Visual Studio for compiling, disassembling, debugging on Windows. Uses GCC/objdump/GDB for compiling, disassembling, debugging on Linux.
Xeno Kovah graduated from the CMU SFS program in 2007 and has been leading a team focusing on sophisticated stealth malware detection (in userspace, kernel, and firmware) and trusted computing at MITRE since 2009. But he's been attending cons since 1999, back before The Shmoo Group had even made a splash at Defcon with their wireless shenanigans. ;) Xeno started OpenSecurityTraining.info in 2011 to host his like-minded colleagues' open source training materials, and he's always looking for new contributors.