Under Linux, I don't know software that won't utilise both processors, providing your kernel is compiled with symetric multi-processing installed (SMP). This tells the core system to use multiple processors, and it's the kernel that passes calls from the software to the processors, memory, etc. Maybe a little out of date, but read http://www.tldp.org/HOWTO/SMP-HOWTO.html
for more info. Also, what version of Red Hat are you running so people can point to exactly how to enable SMP support on your system?