Well...so you have a working system now, with SP3 installed?
The comments about how how sfc /scannow works...can be more logically presented by any number of webpages explaining such.
How To Use Sfc.exe To Repair System Files - http://www.bleepingcomputer.com/forums/topic43051.html
LEARN how to use SFC.EXE (system file checker) in this article! - http://www.updatexp.com/scannow-sfc.html
<<I DO know I had to reinstall sm bus, Ethernet controller, and on board audio drivers ...>>
Then it would appear (to me) that you did a clean install...the only time I install those drivers is after doing a clean install.
A repair install would have left all installed drivers intact, along with programs installed and data files. A repair install provides a new set of system files and removes critical updates which were installed after the SP reflected on the CD.
If I do a repair install of my system today...which has SP3 and all subsequent critical updates through today...all critical updates which have been installed since SP3 will be removed as part of the repair.
Bottom line: If your system is working properly and all critical updates are installed...that's what you want, you can move on to something else