the book...
Assembly Language for Intel-Based Computers By Kip R. Irvine (here's an online preview), it's a bit pricey though.
you can get a nice pdf version of
Art of Assembly by Randy Hyde here, and print it for a hard copy.
a must have for serious hacking is
Ralf Brown's Interrupt List (or an
online HTML Version). and
Iczelion did a fair bit of stuff...
Wikibooks has a pdf on
x86 Assembly.
actually, you can get a great deal of info from poking around Wikipedia, their
Assembly language page has lots of links and the
x86 assembly language page has links to the Intel and AMD manuals!
also check out
The MASM Forum