Well http://www.broadcom.com/drivers/downloaddrivers.php there is no driver for i686 as you can see,
It's a .src.rpm, so you build it yourself on your own running kernel. If you've done that, you've probably ended up with an i686 kernel module in an RPM labelled as "i386". You can get the right RPM packaging like this:
rpmbuild --rebuild --target i686 bcm5700-7.3.5-1.src.rpm
However, I don't think it'll be any different from the package you already have. Anyway, give it a try, then do:
# rpm -e bcm5700 # rpm -ivh bcm5700-7.3.5-1.i686.rpm
Then do "rmmod bcm5700" to make sure the module isn't loaded, and then try "modprobe bcm5700". Then look in /var/log/messages to see what output the module made when you tried to load it.
Paul.