The Asus K7M has a AMD751 Northbridge paired with a Via 686A Southbridge.
Therefore using drivers that are specific to the southbridge (ex: IDE BusMaster drivers) are perfectly valid, and the ones I downloaded from Asus's site are exactly the same as one subdirectory if you unzip the Via 4 in 1 installer.
The machine.INF is just an INF file, it gives windows information about the Via chipsets, windwos will not find information about your northbridge there and will ignore that part.
Absolutely do not use the AGP one though those are northbridge only.
Go download the busmaster driver's from Asus's site if it will make you feel better, they are exactly the same as the ones that come in the Via 4in1.
And now that I think about it, I think Win98 and newer come with the INFs for Via chipsets...