Thanks for the info. Since I'm there tomorrow anyways I'll just look it up at the Spanish library and will base my dicision on what I find. If I find both then I'll let the statistic deside. Until then he's Donquijote do Flamingo for me.^^
Edit: Ok, I went and checked it. Apparently we have too much different books here for Cervantes' story so I quickly dropped checking on them all. However it appears, that both "Don Quixote" and "Don Quijote" are both used in Spanish versions. So I guess both work.^^