found a work around for this on SBS 2008.  Navigate to "C:\Program Files\Windows Small Business Server\Bin\webapp\Remote" on the SBS server.   In that directory you will find a file named tsweb.aspx, right click it and edit it.  Go about 1/4 to 1/3 of the way through the file and look for the section that looks this:

 

sub window_onload()
Dim targetMachineName
Dim version 
On Error Resume Next
version = MsRdpClient.Version
if Err then
  msgbox ControlLoadFailed_ErrorMessage,0,RemoteDesktopCaption_ErrorMessage
  exit sub
end if  
On Error GoTo 0
if strcomp(version,"6.0.6000") < 0 then
   msgbox IncorrectClientVersion_ErrorMessage, 0, RemoteDesktopCaption_ErrorMessage
   window.close
   exit sub
end if

What I did was to comment out the second part of that statement so it looks like this

'if strcomp(version,"6.0.6000") < 0 then
'   msgbox IncorrectClientVersion_ErrorMessage, 0, RemoteDesktopCaption_ErrorMessage
'   window.close
'   exit sub
'end if