I've bought Crucial memory for my Macs a few times over the years and its been fine.
I just bought, on a pre-Black Friday sale from Newegg, 8 GB of PNY DDR3 RAM for my mid-2009 13" MBP and I booted from a memtest86+ cd and ran that. No probs.
I'm also running 4 gigs of Crucial DDR3 PC-8500 in my Mini with no probs.
I think Macs are a bit more picky about RAM than some PCs. But, Asus boards are notorious for being very intolerant of RAM, I think they are worse than Apple in that regard. But I only have anecdotal evidence for that.