I was able to successfully install Flex Data Services 2.0 however the samples only works with Firefox/Mozilla. Using IE returns a blue blank page - it's asking for 8.5 version of Flash Player but after repeated instalations of the 8.5 executable (from the Adobe download site), running the samples under IE still gives the same error. Running the same steps using Firefox was successful the first time.
Check your WINDOWS\system32\Macromed\Flash directory. If there is an uninstall flash executable there, run it. Check that there aren't several .ocx versions here. There should be only one ocx for the debug version of the Flash Player 8.5 (as per the AX installer that ships with Flex 2 Beta 2).