The NiMh's are better than the NiCd's. I have not used a lot of NiCd's, I do believe they might have a little more punch at the very beginning, but they lose charge quicker and do not have as much pop throughout the entire charge/flight.
As for ESC's to go with the E-Flite Park 450 -
http://www.e-fliterc.com/Products/De...rodID=EFLA1025 or
http://www2.towerhobbies.com/cgi-bin...?&I=LXKSY4&P=0 Either would be fine. I have used the E-Flite stuff in one plane and the Great Planes stuff in the other. Both are good quality.
There have been several posts about people converting old PC power supplies into charger power supplies. Just do a search, or scroll back thru the power sources forum.