I need a reliable and free virtual machine to run Linux on Windows, multiprocessor and x86_64. I need a good environment to compile and run ffmpeg and libvpx. I have used Mint Debian under Virtual Box, however it has problems after kernel updates. The guest additions doesn't work any more.
Any idea? Is there a special distribution or other free and quite good virtual machine with near native performance?
Windows 7 Professional SP 1 x86_64 (NT 6.1.7601)