We have an almost entirely IBM shop (except for some Data Domain boxes) and about the only thing we ever replace is failed disk drives - at least for the last three years, that's all I can recall. Especially on their "p" servers. The "x" stuff is much better now as well. We're not a 24/7 shop at the moment, but I have to say that the money we spent buying IBM equipment (which is getting less expensive) was well worth the extra sleep we get from not being in here working on stuff in the wee hours of the morning. As usual, YMMV, but for us, IBM would have to screw up really bad for us to want to even attempt to use another vendor's product.