Warning! It seems this kernel upgrade only works on Debian 5. You should compile a new kernel for Debian 6. See: http://www.yusufozturk.info/linux-server/building-your-own-kernel-packages-for-hyper-v-support.html You can use Debian on Hyper-V with 4 vCPU support. 1) Install a clean Debian 5.0.6 2) Do following: apt-get update aptitude update wget -c http://www.yusufozturk.info/linux/linux-image-2.