I just wanted to put this out there because I didn't think it was very clear. If you want to install Windows .NET Framwork 3.5 without access to the Internet you'll have to perform the installation from your disk:
By selecting the 'Specify an alternaet source path' option. If you try to continue without doing this the installation will fail stating that it was not able to connect to the Windows Update service. If you try to download the installer from the website, filename "dotnetfx35", it will fail with the same error. ( I did read something about being able to perform an extraction on the dotnetfx35 file with a /x switch on installation but I wasn't able to get it working, if you know how this would be done drop me a line I'd love to find out)
The reason for this is that by default the installation will attempt to get the most recent updates for the installation.
Well I hope this might help someone out there.
Oh yeah, you are also able to get this done by running the following command:
DISM /Image:C:\test\offline /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs
Where /Source: is the location in your DVD.