Performance (lots of tables / databases...)

Hi, I am working on a blog system and I am currently thinking of what would be the best DB approach. I have read lots about wordpress and other blog's optimizations and DB structure, but I have not found any mention of having separate database for each blog/user. So, my question is, which one is performance better (talking about 1000 blogs): a) 1000 blogs * 5 (let's say we will have tables like comments, post... for each blog) = 5000 tables in one database ... this is Wordpress default b) 1000 databases (for each blog) each having 5 tables c) 5 databases by 1000 tables - in this case, won't this be an issue when SELECTing like this: [db_comments].testblog, [db_posts].testblog ? Is that a controversial topic? :-/ Thanks for ideas, Martin