Why can't you just select the log in the "Windows Logs" list? MS didn't split any logs into 200+ logs. They are the same as before. They just made a folder that does the filtering so you can drill in and clear a subsection, which was
not as straight forward before.
That's what I thought was the case, but if you go and have a look in %SystemRoot%\System32\Winevt\Logs\ you'll see it's not. There are actually about 60 individual logs on Vista out of the box. These are all the 'serviced' channels from the new event logging
framework and are distinct logs that have to be cleared individually.