Repentinus

I'm interested in creating my own UI. I've downloaded tons but often I get not exactly what I'm looking for. I'll see a piece of it here and say "Wow" that good but it won't have everything I need. Then what I need will be there without what I want. So I figure the best way to get that is to create it myself. Problem is I have no idea what or how to do it. Where would you suggest I start. Obviously my basic two hurdles are learning XML and learning how to apply it to EQ. I was looking at the W3 School thing and looks like I can use that to understand XML but I have yet to find anything that will help me apply it to EQ. Any help would be greatly appreciated.

P.S. How long should I expect before I can see a personally created UI? Weeks? Months? *gulp* Years?