I didn't know the Powershell command - thanks!

This also works:

DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\install\dotNet\dotNetFx35setup.exe

The other thing that might be worth mentioning (because I didn't know!) was that the...

Can I just add something that might seem obvious?

Make sure you've got all the passwords! You *might* need passwords for the application, sa, odbc links etc.

Also, try to find out...