I've built 4 systems around MSI boards:
2x Athlon XP/nforce2 systems
1x s754 Athlon64/nforce3 system
1x s939 Athlon64 (and then later, X2)/nforce4 system
...all of them still work great, and I never once had any issues with stability or reliability, whether running at stock settings or overclocking. Upgrading my socket 939 board from single core to dual core went smoothly, and I've had a few different video cards in it, and I currently have 8 disks plugged into it (4 SATA HDD's in two RAID-0 arrays, 2 IDE HDD's, and 2 optical).
So yeah, if you're concerned about reliability, I'd say go with it, as I've never once had a problem with any of their boards. Can't speak as to the quality of their tech-support though, as I've never used it (though seriously, if you're going to call tech support for anything other than returning a product, instead of just resolving your own issues, then what are you doing trying to build a PC in the first place?)...they have good forums though, full of useful information.