I'm building an [automated] build server requiring the .Net 2.0 and 3.0 runtime. Unfortunately, at my client, they leverage a proxy server. The standard .Net 3.0 SP1 framework redist is really just a bootstrapper. Logged in as a local admin on the box, I didn't have the opportunity to authenticate the installation EXE with my domain credentials. So, the install kept timing out.
Finally, I found this helpful post from Aaron Ruckman on how to download the very elusive, full framework package. It's here, BTW (x86).
I finally get the full installation EXE downloaded to a fileshare, re-run the install and wham--"XPSEPSC: XPS must be installed..." Excuse you? This isn't an XPS...it's a VM.
I found a few MSDN posts here and here outlining the problem. I'm still not clear on what XPSEPSC does (Google yielded little) but you can download it here (x86). After installing XPSEPSC, the framework installed without issue.
Somewhat related, there is no .Net 3.0 SDK, perse. Because 3.0 is more an add-on to 2.0, the SDK remains [mostly] the same as detailed in this post. If you need specific 3.0 tools, look here.