I was wondering this myself.
I notice if you select Windows 7 drivers, the .net support installer for 7 only is what you are presented with.
If you select Windows 8, (puke), you get the smaller non .net installer for both 7 and 8.
I can only assume that Windows 8 has .net 4 built in.
AMD should be more clear on this and explain the situation better so users don't have to waste time wondering and trying to guess what to do here.
ASUS Sabertooth 990FX AMD Phenom II X6 1090T Zalman 9700NT G.Skill F3-10666CL7-4GBXH 16GB XFX R9-280X-TDFD 3GB 384Bit GDDR5 HT Omega Claro Plus Windows 7 Ultimate 64bit SP1 ADSL 6Mbps APC Back UPS XS1000
That wheelchair is for the person that made updating the avatar so difficult :|