>Its Crystal Reports for .NET 2003. We have found a workaround for this where if we declare variables in the SP for the same types/sizes as the parameters, then pass the values of the parameters into the variables and use these in the rest of the SP, performance is as it was in SQL 2000??? Seems to work though

How are you getting the data to your report? Are you loading into a dataset and pushing into the report, or are you pulling the data directly from the report. I prefer the first method, as you have more control over the data.