I'd go for the static looking url myself (mydomain/adulu/seo.html)...I’m just a little “old skool†though. Some people are very paranoid on this front, implementing rewrite rules to change the extensions of all their sites to .html or .htm rather than a dynamic extension or folder structure. Does it make much difference? I'm not really convinced, as I've never seen any significant problem with urls of different extensions so I wouldn't worry about it too much...as with everything, just keep it consistent...and if possible, bring as much as you can up to root level.