sp4 broke perf counters, but easy to fix...

OS perf counters were busted by sp4 (not sure if it's
coincedence or fact, haven't done much testing). Right
after sp4 install perflib started throwing errors for os
counters...
changed "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servi
ces\PerfOS\Performance\Disable Perfomance Counters" from
1 to 0, seems to have fixed it for now. Several reboots
have not disabled os perf counters although rebooting
prior to the reg hack didn't seem to have effect.