Virtualization
 

There is always a debate in Virtualization Softwares in Open Source. I have seen XEN from SuSE and Redhat. Still, I am unable to compare. Anybody can guide me ?

Personally, I like VMWare ;-)

VMware: Excellent functionality (especially Workstation 6.5.x), but proprietary (and pricey with Workstation, Server is free but with fewer features); good support but watch out if your kernel is updated, VMware will need recompiling like most apps that require building kernel modules, and you may be left with a broken VMware install if it's incompatible.
Virtualbox: Fewer features, but (mostly) free for personal use.
I've never personally been a big fan of Qemu, KVM or what used to be Xen. For devel work/network labs I use VMware, for testing new distros out I use Virtualbox. Oh, and incidentally VMware's .vmdk files will (mostly) work in Virtualbox.

Virtual Box is great too.