Windows comes with it's own generic USB drivers I believe
When I got my Sabertooth up and running I just downloaded all the latest versions of the drivers onto a USB stick and stuck it in after Windows booted. Everything worked fine and I updated as needed.
I did decide to use the disc first and then later updated them through a USB as it was my first time. However, you can just go through the USB if you want and bypass the disc
I would install all the drivers and most of the utilities listed in the Downloads section(make sure you know what each utility is, I didnt want one of the wireless tools they gave me so I just unchecked the box).
However, I believe the most important ones that you want to be sure to have are:
LAN driver (else you have no internet)
Chipset drivers, and Intel MEI stuff
Integrated gpu driver
Dedicated gpu driver (if you have one, download from the manufacturer of your gpu)
And be sure to get the Asmedia driver for your 3rd party asmedia ports, I believe that one is best installed from the disc if you don't already have it
Be sure to install the sound, but that's more of a secondary thing after you've done the other key stuff
AI suite is a good one as well
And the intel rapid storage driver if you're doing SSD
If you want to do BIOS update you can also grab that to and throw it on the USB, then flash using the EZ Flash 2 utility in BIOS