[mvanotti]

I think that AMD Developer Guides & Manuals [1] are very good resources for x86_64 System Programming (better than Intel Manuals). They are better explained and focus on x86_64 arch.

[1]: http://developer.amd.com/resources/documentation-articles/de...

[dkersten]

I still have a soft spot for the intel manuals.. probably because I managed to get print copies right before they stopped giving them out :)