I always install the drivers that came with the MoBo as a means of establishing a proven "outta the box" condition. More than once have been told by TS to uninstall a new drivers for one "presumably" invented reason or another. "Did it work with the old driver ?" .... "I don't know" ..... "call us back when you do".
But is is also a good idea as often, you get optical drive software, audio software and diagnostic software which have authorization codes hard coded on the CD which are not on the downloaded versions. When reinstalling the OS, I have had to dig out the old CDs from the Rampage / Formula / Blue Ray equipped builds to get all the little extras working again.
If you buy a MoBo, the on board sound certainly should.... no must ... work outta the box. Updated drivers can always be installed later (and should be) but for troubleshooting purposes, best to establish a "out of box" working condition before calling TS. Only after doing all the Windows updates do I install current drivers.
It's also tough if it's your only computer, as is likely the case here, to download the new LAN driver before you install the one off the CD.
Finally, and this has only ever hit me with audio software .... letting Windows Update install audio drivers has bitten me or one of my users more times than I can count. More than a few times installing the new driver failed and I had to wipe and start afresh.
The only thing I have ever found that I needed to do starting with a new driver and not using the CD was when a new BIOS update is required to support CPU / Memory speeds that weren't supported in early BIOSs