Fans are very cost effective. These fans for example are $14.
Cooler Master Blade Master 120 - Sleeve Bearing 120mm PWM Cooling Fan for Computer Cases, CPU Coolers, and Radiators
http://www.newegg.com/Product/Product.aspx?Item=N82E16835103069
In fact I would do that before considering the CPU cooler. The CPU temperature of 38C isn't that bad. And the improved cooling wiill bring that down.
I would recommend this XFX 750 watt at $74 after rebate.
XFX Core Edition PRO750W (P1-750S-NLB9) 750W ATX12V 2.2 & ESP12V 2.91 SLI Ready CrossFire Ready 80 PLUS BRONZE Certified Active PFC Power Supply
http://www.newegg.com/Product/Product.aspx?Item=N82E16817207015