Installing Squeezebox Server can be done; see e.g.
this search in the forums. I can't tell you if a Squeezebox client can pick up the Windows Home Server native streaming, however.
As for Windows Home Server support, if you have an OEM server (from HP, etc.) you should check with them. Most likely the answer will be some variation on "We support what we delivered. If you install additional software, we don't support that, and if that additional software causes issues with software we delivered, we won't support those issues." There is no free support from Microsoft; if you built your own server, you installed system builder software, and became your own support. The MIcrosoft web site has a section devoted to Windows Home Server with some support links, downloads, technical briefs, etc.
I'm not on the WHS team, I just post a lot. :)
