The default IIS log directory is: C:\WINDOWS\System32\LogFiles\W3SVC1 (it may be different on your machine).
Here are sample log entries in the NCSA, W3C and Microsoft formats:
127.0.0.1 - - [14/Oct/2003:15:44:45 -0800] "GET /som/classes.htm HTTP/1.1" 304 164 127.0.0.1 - - [14/Oct/2003:15:44:49 -0800] "GET /som/vbmodules/ HTTP/1.1" 302 299 22:54:06 127.0.0.1 GET /som/classes.htm 304 22:54:15 127.0.0.1 GET /som/vbmodules/ 302 127.0.0.1, -, 10/14/2003, 15:50:50, W3SVC1, LPNEWPORTABLE, 127.0.0.1, 0, 397, 164, 304, 0, GET, /som/classes.htm, -, 127.0.0.1, -, 10/14/2003, 15:51:00, W3SVC1, LPNEWPORTABLE, 127.0.0.1, 0, 448, 299, 302, 0, GET, /som/vbmodules/, -,