Sometime ago I answered a newsgroup question concerning How to find out what version of SharePoint is installed on a server, and then the other day I had to ask myself the same question, so instead of looking through all my emails everytime, I've decided to put the information on my blog - just incase you too may need to find out. I've created an article, so I can update it as new versions are released.
With that in mind, I've included the version number of Windows Server 2003 R2 beta. You can download a beta version of R2 at http://www.microsoft.com/windowsserver2003/R2/trial/installinstruct.mspx. It needs an evalution copy of Windows 2003 which you can obtain from http://www.microsoft.com/windowsserver2003/evaluation/trial/default.mspx. However take note that the evaluation copy of Windows 2003 server, from my experience, takes a long time to download. It was not a problem of the size of the pipe at my end but looks like its a restriction at the microsoft end.