I no longer get reply notification emails, so didn't see your post until just now. Use the WD diagnostic software to run the long test on that 2TB drive before putting it into service. While you're doing that, make sure the 1TB is running version 11.0k (or later) of the TiVo software (look in system information). If it's an earlier version than k, let it connect to TiVo until it updates. That's necessary for it to be able to handle a 2TB drive. Then take the 1TB drive and the 2TB drive, hook them up to a PC running XP or later with WinMFS loaded, boot into Windows, open WinMFS, select the 1TB drive, click on mfscopy, tell it the 2TB is the target. If it offers you the chance to NOT use the "optimized" format/layout for partitions, DO NOT accept that offer. You can increase the swap partition size if you want to--the way I see it, can't hurt, might help someday down the road, but others don't bother and seem to be getting along okay. I set it to 1000 or 1024 It'll take a while for mfscopy to finish, and it may well look like it's frozen, but it's not, just let it run 'til it finishes. It'll say you have extra space and do you want to expand. Say no. Then select the 2TB. Then click on mfsinfo, and make sure everything looks okay. There will be a big Apple Free partition. Then click on mfsadd to expand into that space. For some reason you have to do it in two steps instead of the one step it offers to you. The reason to copy the 1TB is that it already knows the TiVo Service Number of the TiVo and won't have to go through the error 51 fixing process the way you'd have to with using someone else's image.