With a laptop, you must rig the old drive in a usb enclosure and connect via a usb port since there's no room in a laptop to install a 2nd hd. Any of the major brands are ok, Seagate, Western Digital, Maxtor, IBM. etc. I get them off fleabay for 1/3 the price most retailers sell them. And you might want to consider buying one that has more capacity than the old drive.
You can also buy a cheap device that will accomplish the same thing as an external usb enclosure. It's simply a cable with the right connectors on each end that will attach to the drive and to a usb port and comes with a wall-wart power supply. It's called a USB 2.0 to SATA + IDE converter and they are less than $10.00 plus the shipping. You can see one on Geeks website:
This one will handle both SATA AND IDE drives. I keep one on hand just for that very purpose. The most handy device ever to come along since pockets on a shirt... lol.
You have one other option but it requires quite a bit of extra space on the old hard drive and that's to install Windows to a different folder than the default folder of C:\Windows. But I would only use that option if everything else fails. The downside to this would be you would have to uninstall and re-install all your programs but at least all your data would still be intact. It would create a brand new registry so it wouldn't have any data about your existing programs.... that's why it would require re-installation of all programs.