Below is an SQL query that works. It gives me the count of results, maximum result and minimum result for a given trial with the given the set of where constraints.

Code:
SELECT Series.Short, Trials.Rego, Trials.TrialID, Count(Varieties.TestName) AS CountOfTestName, Min(Results.Results) AS MinOfResults, Max(Results.Results) AS MaxOfResults 
FROM ((Trials INNER JOIN (Series INNER JOIN Samples ON Series.SeriesID = Samples.SeriesID) ON Trials.TrialID = Samples.TrialID) INNER JOIN Varieties ON Samples.VarID = Varieties.VarietyID) INNER JOIN Results ON Samples.SampIDBarcode = Results.SampleID
WHERE (((Series.Year)>"2003") AND ((Results.DoneYet)=True) AND ((Samples.SampleTypeID)=1) AND ((Varieties.TestName) Like "WAWHT*" Or (Varieties.TestName) Like "IGW*") AND ((Results.TC)="WP"))
GROUP BY Series.Short, Trials.Rego, Trials.TrialID;
What I need is to get the variety.testname for the result that happens to be the maximum and the variety.testname for the result that happens to be the minimum.

I don't think that is possible to do in this one query so if someone can even suggest a query to give the variety.testname that happens to have the maximum result for a trial that alone would be enormously helpful.