i5 2500k vs i7 2600k

I’ve just built a budget system ($400) i5 2500k, GA-H61MS2H for Windows 7 and Mac Lion 10.7.3 because our i7 920 1366 x58 motherboard died. To replace a new x58 motherboard would run me about $120 – $200 and the system will hog over 189W when I encode a movie, it was fast but I