ubun2^beta

I have VirtualBox 3.0.12 r54655 installed on my ubuntu 64bit desktop machine. When i launched the virtual box, it prompted that there is an update available and pointed me to download the .deb file virtualbox-3.1_3.1.2-56127_Ubuntu_jaunty_amd64.deb and i downloaded the same.
 
When i right clicked on the file and selected "Open with GDebi Package Installer", it is giving me the following error message
 
Error: Conflicts with the installed package 'virtualbox-3.0'
 

On ubuntu 64 bit machine i am running 64 bit virtual box. I installed windows 7 on it but i choose the hard disk size as 10 GB. Looks like it wont be sufficient enough. How to increase the hard disk size?

Please help installing 64bit version of sun virtual box 3.0.8 on my ubuntu machine. I am planning to run windows xp inside it, is it possible?