This should probably be posted over in the BI forum.
I have heard some people that are using the old 2.0 web parts have some issues with rendering SSRS reports in Native Mode. I would definitely do some work on a development machine or test server prior to working with the 2.0 Web Parts against 2008 RDL files.
If you are looking for integration between SharePoint and SSRS, I'd really recommend setting up an instance of SSRS in SharePoint Integrated Mode (if possible) and hosting your reports in SharePoint using the "newer, more supported way". Information regarding what that involves can be found here.