General resources
++As far as I know, any 2.5" SATA laptop-sized drive will work. +I personally prefer hard disks but most people recommend solid-state drives for their superior speed, especially in random access, and power draw, among other very strong advantages. +
++Most of the eBay listings for X200Ts don't have hard drive covers or caddies. +You will want a caddy because it makes it much easier to get a drive out, and because it spaces out the drive in the space provided and provides some (minimal) amount of shock protection. +This is especially good for hard disks as you don't want those moving around in your laptop chassis, even if there's no risk of them being disconnected. +
++In a pinch you can use cardboard to space out a drive. +I made out okay using folded cardstock given that my X200T was going nowhere except my desk. +You should not do this for long periods, not really because there's some risk that increases as time wears on but just because in general it's stupid. +
++The same rubber rails that go around the hard drive, and the same metal thing that you screw onto the drive that has the black ribbon attached used to pull the drive out, are used for the X200, X200S, X201T, X201, X201S, X201T, T420, T420S, T430, and T430S, as far as I know. +Rubber rails for the X220T did not work, nor did the bay cover for the X220T work for the X200T. +