Yeah, macs are finicky when it comes to ram (which is a good thing, really... they're engineered with tighter ram tolerances than most wintel boxes). I've always bought my ram from ramjet.com. They guarantee that their ram is fully compatable with all macs' current firmware. Good prices and excellent service. Never had a problem and I've bought ram for half a dozen macs from them. I've also heard good things about crucial.com.

And as you found out, DiskWarrior is an absolute savior. You don't need to buy ram from Apple. They'll ream you. Go with ramjet.com.

Merry Christmas!