This
nifty program will
natively execute an
x86 operating system (
emulating certain hardware and
instructions) in a
GNU/Linux X window or
Windows NT window.
From my personal experience, there is no noticable speed decrease, if anything, Windows seems to run faster under GNU/Linux. :) but it has to emulate the drives and display, among other things, so yes, it's slower
Sadly, though, this piece of
software is not
free.