x86 SSE instructions

[Kevin Nomura]

I'm looking for a version of gas that supports SSE
instructions, for example "prefetchnta (%edx)".
The latest binutils at sourceware.cygnus.com is 2.9.1.
It doesn't support this instruction as evidenced by

   fgrep prefetchnta binutils/opcodes/i386-dis.c

However the assembler installed with redhat 6.1
accepts this instruction.  The source package
"binutils-2.9.5.0.22-6.src.rpm" from rpmfind
understands SSE.  

Where is the corresponding "official" release of
binutils that more or less matches this 2.9.5.0.22
thing?

Kevin