While it may be pricey and/or time-consuming, I recommend something called a Magic Bridge or a similar product. It is a USB adapter for an internal hard drive. If I recall correctly, it's about $40 online or at your local store, but trust me, it's definitely worth it if you have more than one running system (especially when Windows crashes and you need to reformat).
I use it at my job all the time, however, be sure that the unit supports IDE interface, because there are some SATA only units.
Hope that this helped.