Just increase the RAM of my ubuntu host to 8G and found that VBox 3.2 is out.
Formal name changed as per acquisition of SUN by Oracle.
Exciting news include ‘Experimental support for Mac OS X Server guests’ and performance for 64-bits host with VT-x enabled guest will have better performance, CPU and memory can be increase/decrease even when guests is running (depends on platform of hosts and guests). Multi-monitor guests setup is supported for Windows guests.
My Adventure with VirturalBox 