Thank you for the replies.
I do not have much money and doubt whether I will be able to afford much at all so I was expecting to have to do this myself. (mind, this is only for fun and not essential)
Thank you for the link also.
Where does the design of a desktop come into designing an OS and/or Kernal?
What do you mean, the design of a "desktop"? What's a desktop? That's a rather general term. Of course, you can see where it matters, in that features like multitasking are considered useful (as opposed to batch processing). Then you see features like threads becoming more prevalent as a result of the needs of programmers.
If you are really interested in knowing the nitty-gritty of operating systems and building one of your own, get your hands on "Operating Systems Design and Implementation - by Andrews S. Tanenbaum." You can get all the concepts related to OS and the appendices contain the source code for an operating system called "MINIX".
FYI, Linux has evolved from MINIX, by applying all the recommended improvements to MINIX which this gentleman avoided just to keep the MINIX OS small and academically interesting.