I'm going to get a couple of internal new HD's fitted for a couple of late model emacs (1.25 and 1.42). But I'm not sure what to look for when buying them. I was going to go for 250Gb drives. And I know it should be 7200 rpm but I'm not sure about the size, is it 3.5" or something else. Also is there anything else I need to watch out for like special connections or any other technical thing. I want to bring the drives and the emacs to the workshop and I don't want them telling me I've brought the wrong type of drive. As a side issue when I get the old drives back I'd like to reuse them as external drives. Is this a complex procedure or is it just a matter of getting a case and slotting it in.