The test results that we present are the average of five runs. The machine we use to run the tests has a Intel Pentium 4 CPU 2.40 GHz processor and 1 GB of RAM. We run the benchmarks on three operating systems to compare the performances of different rule engines on each of them. These operating systems include Windows Server 2003, CentOS 5 and Solaris 10. Our results show that none of these operating systems has a consistent advantage over the other two.