Can Seem To Get Delete And Exist To Work Right

Hi all,
I am writing a test result database in SQL 2K5 and one of the features I want to implement is a stored procedure that deletes the oldrecords while preserving a set number of records, the following is what my SP looks like


Procedure [dbo].[CleanResults]

@RecsToKeep bigInt,

@Output Int output

as

Declare @Date Datetime

Declare @Count bigint

set @Date = getdate()

Select @Count = Count(UniqueID) from [Main]

Print 'THE COUNT IS'

print @Count

if ( @Count > @RecsToKeep) begin



set @Count= @Count - @RecsToKeep

Print 'THE Number to delete is'

print @Count

select TOP(@Count) UniqueID from Main order By [Main].[TestDateTime] desc



Delete from [Main] where exists (select TOP(@Count) * from Main order By [Main].[TestDateTime] desc);



set @Output = @Count
end

else begin

set @Output = -1

end


whats odd is that the select staement will evaluate correctly and return the oldest record @Count record, however the delete stament removes all the records. An advice would be appriciated.

Thanks Christopher

PS Any advice for using TOP with variables in MSDE 2k (as opposed to 2k5) would be appreciated