Logical Disk missing in Performance Counter
From Microsoft KB #253251: http://support.microsoft.com/?kbid=253251
In Windows NT 4.0 all disk counters for Performance Monitor were turned off by default. In Windows 2000 the Physical Disk object is turned on by default and the Logial Disk object is turned off by default.
To obtain performance counter data for logical drives or storage volumes, you must type diskperf -yv at the command prompt, and then press ENTER.
This causes the disk performance statistics driver used for collecting disk performance data to report data for logical drives or storage volumes. By default, the operating system uses the diskperf -yd command to obtain physical drive data.