Installing i386 apps via yum on an x86_64 install

[Frank Pineau]

Ok, so, there are a few apps that don't work well under x86_64.  Mplayer
(because of the 32-bit codecs), Firefox, java, and a few others.
Obviously I can download and compile from source, but is there a safe
way to install 32-bit rpms via yum without borking the rest of my
system?  Mplayer-i386, for example, has a bunch of i386 lib dependencies
which are obviously not installed, so even compiling from source would
end up being a pain.