If you want to be a kernel hacker,first of all, you should have source code of the kernel.There are two kinds of source code. One is distribution (stock) kernel and another is fresh main line kernel.If you want distribution specific kernel then you could get it from their mirior.You have to look at the distribution specific mirror and it depends on distribution to distribution.These kind of kernel source code are modified according to the distribution needs.The problem with these kind of kernel source code are 1) Distribution dependent 2) Not 100% percent coustomizable It is not good choice to start with any distribution specific kernel. To get fresh new kernel you should look at [www.kernel.org] site. This is the official site for Linux kernel source code archive. If you can see, the main page of this site itself has a very good documentation about the latest and stable version of kernel source code.So just get it which you want. Fresh new kernel are alwayes 1) 100% customizable. 2) Distribution dependent. 3) Current device supported. You could find all kernel version archives at ftp://ftp.kernel.org/pub/linux/kernel/2.6