With a cooler like the Buffalo, i wouldn't expect much from it..but getting a temp drop of 44 on idle compared to the 50 (with what u had previously is a HUGE difference). You just made ur processor live a few more years... Getting temps lower than that would mean investing in a more expensive cooler - the Cooler Master Hyper 212+ is a popular and GOOD cooler, i was recommended that a few days ago.
but thas good temps as far as i'm concerned. to lower ur temps a bit more i'd need a lil more details on ur casing
since i cant find the specs page even after googlin it - but i guess its mATX form factor - correct?
i came across this but is this anywhere close to yours...in size at least
http://www.pcmag.com/article2/0,2817,1939274,00.asp
oh and please mention your ambient/room temp