Well, it has also to do with luck i guess...in the top 50 list there is someone with several blocks on his name and only hashing with 20Mhash/s

Yeah, but he could have been hashing with 20 mhash since 2010 and found blocks when it was still profitable to mine with a cpu.
Or he could have started last month with 100 ghash, but is now having network issues, and can only mine with his laptop's 7750 @ work...lol
There is a lot that list doesn't say.
