if you want speed then make sure that any drive your get is 7200rpm instead of the more standard 5400rpm, if you look at Western Digital Drives (my personal preference) the Scorpio Blue line runs 5400rpm and the Scorpio Black runs at 7200rpm, the transfer rates across different vendors doesnt change very much, just make sure that its 7200rpm, with the WD's the largest that will fit is 750gb (thats what I run), I have heard of someone putting in a 1tb but there are some mods required....the max size is 9.5mm for a 2.5in drive the 1tb is 12mm and like I said needs some mods to fit..as far as migrating from one drive to the other, some of the drives come with software for this, others do not, you can use Norton Ghost which works well and Acronis Disk Director Suite will do the job also