Basically, SharePoint says it needs .NET Framework 3 but when you search on that version on www.microsoft.com, it guides you towards v3.5
Cheers, Rob.
It is a separate version.
But it includes .NET Framework 3.0 SP1 and 2.0 SP1, for backwards compatibility.
It is an extension to .NET 2 and .NET 3. You can not have 3.5 without also having 3 and 2. Install 3.5 and any updates and sharepoint will be happy.
.NET 3.5 family update is available on microsoft update and is .NET 3.5 (which includes service pack 1 version of .net 3 and 2) and some updates on top of that to fix compatability problems introduced by the service packs.
3.5 is both a separate product and an upgrade - if that makes sense.
The same install will either upgrade an existing installation or do a full install if there's no version already installed.
As far as IIS is concerned, ASP.NET 2.0 3.0 or 3.5 use the same version of the CLI so they are undistingable