Check to ensure processor IS 64 bit http://www.cyberciti.biz/faq/linux-h...64-bit-or-not/
You can use that page to see if you've got a 64bit OS also.
If you have 64bit HW, but 32bit OS, you'll need to re-install a 64bit OS; you cannot 'upgrade' to 64 bit.
I doubt that upgrading 23->64 bit will solve the sound issue, but no harm in getting 64 bit if your HW supports it.
RHEL based systems will handle 64 & 32 bit apps on a 64 bit OS.