mdadm or LVM for software raid?

[Tom Horsley]

I see mdadm is one cryptic way to setup a software raid
and I saw some note somewhere that says LVM also supports
software raid1. Any reason one is better than the other
(or does LVM not actually do raid and I misread something)?

My BIOS also has some sort of Intel raid helper hardware
thing, but I can't imagine there would be a good reason
to use it since all the data would become nearly inaccessible
trash if I have to replace the motherboard :-).