Another fan and placement?

Just getting ready to build first computer...parts are on the way. I am clueless, but learning...

450W psu in top of case preinstalled, 120mm fan in back, cooler and cpu fan...and, case seems to be fairly well open/ventilated.

Do you think I should get another fan for front to be safe? I do plan on overclocking for video editing / photoshop (not for gaming)

1) how do you know you need more fan(s)? Is it simply monitoring temp or is it commons sense

2) should I get an additional one for front to be pre-emptive?

3) where in front, top or bottom?


Thanks


$120.00 motherboard ASRock Z68 PRO3-M http://www.newegg.com/Product/Product.aspx?Item=N82E168...

$205.00 cpu Intel Core i5-2500K Sandy Bridge http://www.newegg.com/Product/Product.aspx?Item=N82E168...

$0.00 psu antec vp 450 http://www.amazon.com/Antec-Cost-Efficient-Tower-Case-V...

$85.00 cabinet Antec Mid Tower Case VSK-2450 http://www.amazon.com/Antec-Cost-Efficient-Tower-Case-V...

$109.00 hard drive WD Caviar Black 1.5 TB http://www.amazon.com/gp/product/B004CSIFG2/ref=olp_pro...

$45.00 ram Patriot Signature 8GB (12800) http://www.newegg.com/Product/Product.aspx?Item=20-220-...

$138.00 monitor 23" SAMSUNG 2333T http://www.quill.com/samsung-widescreen-monitors/cbs/24...

$23.00 dvd drive LITE-ON 22X DVD±R DVD Burner http://www.newegg.com/Product/Product.aspx?Item=N82E168...

$0.00 OS Windows 7 home 64bit http://trinitysoftwaredistribution.com/mm5/merchant.mvc...

$29.00 cooler Cooler Master Hyper 212 Plus http://www.amazon.com/Cooler-Master-Hyper-Sleeve-RR-B10...

$0.00 graphics card -----------