If it is an older version of WP, you need to find out what version of WP generated the database, as WP upgrades the DB most times the files are upgraded and you should incrementally upgrade to also upgrade the database.
Look in the wp_options table for option 711 and see what the version is; option name will be site_transient_update_core and the value will be the download link, i.e. http://wordpress.org/wordpress-3.2.1.zip which means the version is 3.2.1
Find the version and leave a comment below.
Depending on the age of the version, you need to do manual, incremental upgrades to get to at least 3.0 where you can use auto-update.
If you import/move a DB, no need to run install.php. Just upload all WP files and folders. See Moving WordPress « WordPress Codex