It should run just fine on a 2-4 CPU box.
According to the HOW-TO (you should really learn how to use google...), the 2.2 series kernels should theoretically work for up to 16 CPUs on an Intel machine. Redhat 7.3 uses a kernel in the 2.4 tree, so I can't be 100% sure of any changes.
Here is the HOW-TO I am referring to:
http://www.tldp.org/HOWTO/SMP-HOWTO.html