Where do I find the FTP logs?

[supra2800@]

According to the components page in Plesk, I'm using Microsoft FTP Server 6.0. And in the IIS settings within the server, the log files should be put in \windows\system32\LogFiles and named as MSFTPSVC, but there's no such folder there, only a bunch of W3SVC folders and SMTPSVC, Shutdown and HTTPERR.

Any idea where I can find the logs for the FTP? I need to figure out a possible hacker attack or if it's just a matter of poor passwords. One of my customer sites suddenly has an iframe within the index.html, trying to load sites that contain malicious code.

Thanks.