Maximum size of Report Parameter

I have a report which I need to call from ASP.NET page. I'm trying to use reportviewer control that came with Reporting Services 2000.

The report has a parameter which accepts more than 5000 charecters size string. But when I run the report the report viewr never responds. But if I limit the size to around 700 charesters it works fine.

So, my question is what is the maximum size allowed to set the reporting services report parameter value ?

Is there any difference in SSRS 2000 and SSRS 2005 related to this issue?