Get the best one you can afford. Not much else I can say, read some reviews for monitors in your price range. The currrent monitor I have I absolutely want to smash to pieces because of the viewing angles. (which are bad even for a TN panel)
But yeah get the best monitor you can afford. Why bother building a system and having a crappy quality screen ruin the whole experience.
Edit: Oh I think I misunderstood. I would grab a 1920 x 1080 unless you can find a cheap 1920 x 1200 at a comparable quality level.
CPU: Intel Core i5-3470 3.2GHz Quad-Core Processor ($149.99 @ Microcenter)
CPU Cooler: Cooler Master Hyper 212 Plus 76.8 CFM Sleeve Bearing CPU Cooler ($14.99 @ Newegg)
Motherboard: ASRock H77 Pro4/MVP ATX LGA1155 Motherboard ($87.55 @ Newegg)
Memory: G.Skill Ripjaws Series 8GB (2 x 4GB) DDR3-1600 Memory ($24.99 @ Newegg)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($69.99 @ Newegg)
Video Card: EVGA GeForce GTX 660 Ti 2GB Video Card ($249.99 @ Newegg)
Case: Corsair 400R ATX Mid Tower Case ($59.99 @ Newegg)
Power Supply: Corsair Enthusiast 650W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply ($49.99 @ Newegg)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer ($15.98 @ Outlet PC)
Monitor: Asus VS239H-P 23.0" Monitor ($164.99 @ Newegg)
Operating System: Microsoft Windows 8 (OEM) (64-bit) ($79.98 @ Outlet PC)
(Prices include shipping, taxes, and discounts when available.)
Much better perfomance for 1080p.
1º the cpu is much better, 2º the gpu is from a actual generation and its better than the 570 and consumes less power, 3º 8 gb 1600 mhz, better case, and the most important thing it doesnt have a crappy psu like the one you chose which i doubt it will powerup the 570 gtx.
With a ips 23" led 1080p monitor.
I have an HP x2301, which is a 1080p LED monitor. It doesn't have IPS, but it is one of the best monitors I've ever used. It looks amazing, it's thin, and it costs $180, which is a great price for this monitor.