Yes you need a new ECU among other parts. Sport Compact Car has a good article on how to do the swap(
www.sportcompactcarweb.com). The LS/VTEC is pretty easy, but there are a lot of parts to buy. A whole lot cheaper than a K20. If you look around enough, you can find a B18C1(GS-R) for $1500. They will drop right in, but you need all the accessories and the ECU.