CMS-Blog system

Hi, I am working on CMS-Blog system, which will be using approx. 10 000 users. I have a basic question - I believe there are only two options - which one is better? 1) having separate databases for each blog = fast (problem: what if I will need to do search in all of the blogs for some article?) 2) having all blogs in one database - that might be 10 000 * 100 articles = too many rows, but easy to search and maintain, hmm? --- I am thinking of having some file etc. "cms-core.php" in some base directory and every subdirectory (= users subdomains) would include this "cms-core" file with some individual settings. Is there better idea? I appreciate your discussion on this topic. Martin Zvarik