Get the 2400 ($149 at microcenter), and an AS Rock H61-M/U3S3 motherboard ($75 at newegg), with $30 saved on the CPU, you have $155 left for a monitor. I'd suggest the Acer 21" 1920x1080 model for $117. Get the $29.99 Rosewill R102 case and an extra 120MM fan, and you're good to go. the 560ti fits in the micro atx case easily.
well i think you should overclock since it is really easy with the new i5 2500k you can hit 4.4ghz w/out even touching the voltage just upping the cpu multiplier to 44x. also you get 40$ off any 1155 motherboard with the purchase of an i5 2500k at microcenter i think you should get this one- http://www.microcenter.com/single_product_results.phtml... so this motherboard is really 100$ after mail in rebate