well, for the SQL log, exactly where the logs go is configurable...when you first install the server, one of the options is to decide on the folders.
it defaults to a certain path, of course if not changed @ setup
where it is right now, you can find out via TSQL like this:
SELECT SERVERPROPERTY('ErrorLogFileName');
you can see the current setup in the facets:(See the ErrorLogPath this screenshot was from showing how to change the default paths for databases and backups);
to change it after installation, i believe is a registry edit and a stop and start of the server is required.
Lowell