you can query the LoadTestComputedCounterSample view.
select
* from dbo.LoadTestComputedCounterSample where loadtestrunid = @LoadTestRunId
where
MachineName = @Machinename
and
CatagoryName = @CatagoryName
and
CounterName = @CounterName
and
InstanceName = @InstnaceName
You can get the Load Test Run ID from doing a select * on the LoadTestRun table in the load test database.
This will get data for the Machine Counters, the catagory, Counter and Instance names are the same as in Perfmon.
If there is no instance name for a counter in Perfmon you can leave the last line of this query off.
Hope this helps
Paul