Wow. You can't create an OS with no experience at all, it's just not possible. It takes a lot of effort and some very developed skills to put together a viable operating system (XP took 500 man years to code the initial release). No amount of forum advice will do it unles you get pointed at a very long tutorial.
If you're really interested in creating an OS I'd suggest starting with linux. It's all open source so you can take out the stuff you don't care about and add/customize whatever you want to it. This is what one of my early "mentors" suggested to me when I first started talking about complex programming projects.
It will be a lot of trial-and-error so you want to do it on a dedicated system or a virtual system (virtual box for free or VMware paid) so you don't have to tie up your main system with constant restarts and technical issues.
With good programming experience you can write an "operating system" in a week or so but it will look a lot like DOS with a lot less features.
I think the core of the OS (the kernel) would be coded in basic, but the rest could be in any language you're comfortable with. I've seen OS front-ends done in Java, and I even have a contact at macromedia (adobe now, but he was with them before the buy-out) who's working on a flash based GUI.