Check this out and they are letting you sign up for the next trial!
Sign up: http://connect.microsoft.com/WindowsHomeServer
Good news! Windows Home Server has reached the Beta 2 milestone! While previous releases have been tested by 1000+ Microsoft employees and some of our hardware and software partners, we are now starting to invite a broader group of external testers to participate in Beta 2.
People that are interested in participating in Beta 2 can register here so we have their names as we steadily expand the program. We can’t guarantee you’ll be invited to participate right away (or at all), but if you’re interested get yourself registered. Keep in mind that Beta 2 does not really represent the “consumer experience.” Most consumers will ultimately buy Home Server as an integrated hardware/software solution that’s very plug and play, e.g. the HP MediaSmart Server. Beta 2 is software only, of course, meaning evaluators will need to know how to install and configure a server operating system. Beta 2 participants will also need a dedicated machine for Home Server – Pentium 4, 512 MB RAM and two or more internal hard drives with at least 300 GB primary system hard drive is recommended – and at least 2 client PCs and a broadband connection.