24/7, yes...I was saying that "certified" is a marketing term which has no measurable standard. With respect as to why wouldn't manufacturers claim all hard drives are suitable for 24/7 use, one could cynically argue that it would remove their ability to generate a higher margin for a like product...similar to charging more for a blue car than a white one. But I'm not quite that cynical. . I do know that enterprise class drives are actually built differently. I also know that dedicated A/V drives are also built slightly differently...however as mentioned, TiVo cannot (or perhaps doesn't need to) take advantage of the additional features. MTBF is in fact higher for enterprise class drives but we need to keep in mind the A/V dedicated drives we're talking about are not enterprise class. Anyway, I think we agree that a good A/V dedicated drive is a good investment. From personal experience (I'm using both) and several years of posts on the TCF and other forums, there doesn't seem to be any empirical or really even compelling evidence that they perform any better or worse or last any longer than the recommended "standard" hard drive options. That said, the more positive posts I read about 2TB upgrades here...the more difficult it is not to jump on the bandwagon! Thanks very much for your continued hard work on this...you have a lot of happy "customers" (of which I will likely be another pretty soon).