The linux kernel 2.6.30 DEB files can be found at the following website:
You have to install 3 files in the ORDER listed:
linux-headers-2.6.30-020630_2.6.30-020630_all.deb linux-headers-2.6.30-020630-generic_2.6.30-020630_amd64.deb linux-image-2.6.30-020630-generic_2.6.30-020630_amd64.deb
When clicking the files you get a choice to install them using gdebi or to save them. Choose install.
There is just one thing: the order in which you install them is important. Don’t panic: when choosing the wrong file first in gdebi it will tell you it is missing some dependences. The right order is the one written above.
When done simply re-boot and you’ll see the new kernel mentioned at the top of the Grub list.
On Ubuntu forums the kernel listed above was recommended as STABLE. I’ve done this myself. You’ll have to recompile the VirtualBox Kernel Module, and VBox will give you the sudo command to do this when you try to launch your VM…..easy. Nvidia will be taken care of automagically.