Bottom line is that unless you wipe your original TiVo hard drive, you'll still have all of your recordings. I always recommend putting the original drive on the shelf as a back-up JIC. Worst case you can always pop your original drive back in to watch them (or if you have to send your box back to TiVo if something else fails while it's under the one-year parts warranty). Your best bet is to connect your drive(s) via SATA to your computer's mother board. Most MB's (within the last five years) have SATA connectors. That will speed up the process using MFSCopy. How long it takes all depends on how many recordings you have, SD Vs HD, their length, etc. It may only take an hour or less...might be several hours. If you use USB it will of course take longer. You do not have to clear and/or delete anything when using WinMFS to create a larger drive (copying existing content or not). All of your settings including cable card info, SP's, etc. will be transferred over.