[ubuntu] Done It Finally

Well all i've done it, i've finally switched to linux, switched off windows as my main source....
But I would like to run a win OS as a VM, not as a dual boot.....

Therefore, could anyone reccomend which is the most reliable, simple to use VM for ubuntu v12.10 please?
& if you could point me too a download site this would aslo be appreciated!!!

Thanks team (in advance)