New York Stock Exchange Runs Trades On Red Hat Linux (InformationWeek)

Mission critical stuff like this you DO NOT screw around with. If the vendor supports their
package under AIX, HP-UX, Red Hat Enterprise Linux, and Solaris, and nothing else, then those
are what your choices are.

That the package will work under CentOS, *BSD, etc is irrelevant. You don't want to be on the
receiving end of the TPTB's wrath if the package breaks (for any reason) and vendor refuses to
help you because you put in on CentOS 5 instead of RHEL5.