well, I bought a 128 meg stick of PC133 from crucial over a year ago, and just recently, I screwed up and put in in BACKWORDS and it totally fried the ram and ruined the stick.
I called crucial, they told me to mail it in and gave me an RMA #, and less than 2 weeks later, I had a brand new stick of ram waiting for me when I got home from work. Crucial has MARVELOUS warranty and service. A lot of ram has a lifetime warranty, but nobody matches service like crucial.com. NOBODY.