Parallels Desktop for Mac – run Windows on your Mac OS X at the same time without rebooting!
Parallels Desktop for Mac is the first solution for Intel-Macs that give you the flexibility of running Windows or Linux on a Mac simultaneously without rebooting.
The upgraded 3.0 version delivers completely seamless user experience, native hardware experience and protection against mishaps.
Centos provides a free enterprise class computing Linux platform to anyone who wishes to use it.
The Free Enterprise Linux from Centos is built from publicly available open source SRPMS provided by a prominent North American Enterprise Linux vendor. CentOS conforms fully with the upstream vendors redistribution policies and aims to be 100% binary compatible.
Usually, an updated version of the Centos Enterprise Linux is available within 72 hours of Red Hat releasing a fix in their enterprise version.
So effectively, the Centos Linux is as good as a free Red Hat Enterprise Linux .