http://www.virtualbox.org/
I tried it on
1. Windows XP SP3 hosting Ubuntu 8.04 LTS
2. Fedora 9 hosting Windows XP SP3
Found it not bad...similar function to VMware...but
Open-Source...so introduce to U all...less troublesome than
dual-booting.
Source : http://www.virtualbox.org/wiki/VirtualBox
VirtualBox is a general-purpose full virtualizer for x86 hardware.
Targeted at server, desktop and embedded use, it is now the only
professional-quality virtualization solution that is also Open
Source Software.
Some of the features of VirtualBox are:
A number of extra features are available with the full
VirtualBox release only (see the "Editions" page for
details):