I'm also new to this, and I fired mine up last week for the first time, and thought my steppers were hot, also, and contacted two well respected individuals on the subject, and they both said it's normal. Yes, you need the right resistor, and the one guy, Ahren from CNCrouterparts.com--he's the guy who sold me the steppers--said he could send me different resistors that would resist more, and keep the motors cooler, if I'd like them to be, but that it would be fine if I just didn't worry about it.