I'm on my second MSI mobo(k7n2-l NForce 2), my first was a K7 Master(AMD 761). The K7 Master was rock solid stable for 16ish months running 24/7 at 100% CPU load(SETI and UD), then it began to get flakey. It ran a couple more months with the occassional lockup, then one day it just shutdown and that was it. Fortunetly, there was a 2 year warranty for it so MSI replaced it with no hassles. During the RMA process(about a year ago) I bought my current MSI mobo and it has also been rock solid running 24/7 100% CPU load(SETI).
2 of 3 other systems in the house also use MSI mobos(1 k7n440-original NForce, 1 other k7n2-l) and are fine(though the k7n440 is plagued with heat issues). In my experience, MSI mobos are rock solid, at least for a time, probably best for those who upgrade their mobo on an annual basis and don't want to pay a Premium price. If you want 3-4 years from your mobo, get an Asus.