Building a gaming PC for the first time: how is this selection of components?

I have read a few articles regarding building PCs, and has lead me to select this combination of components based on my needs. I was hoping for a decent gaming PC that can run stuff at 1900×1080 at decent settings (if not the best). I also use my computer to multitable poker, but I was assuming that by getting something that can run games pretty decently then it would take care of that at the same time. If I am wrong in this thinking, let me know.

I am still pretty inexperienced concerning building PCs so I wanted to check with our computer flutherite experts before going ahead and buying stuff.

So my questions are:

Is this selection of components good?
Are there other things I have missed?
Are there better products for the same price than what I have selected?

And here is the list of components.

NZXT Hades PC Case:
http://www.cclonline.com/product-info.asp?product_id=51183&tid=frooct#

AMD 785g AM3 DDR3
http://www.dabs.com/products/asus-am3-amd-785g-atx-ddr3-audio---gigabit-ethernet-64N8.html?refs=48620000-432790000

AMD Phenom II 550 3.1GHz 7mb
http://www.dabs.com/products/amd-phenom-ii-x2-550-3-1ghz-skt-am3-l2-l3-7mb-80w-pib-6NCB.html

Crucial 2gb ddr3 ram
http://www.dabs.com/products/crucial-2gb--240-pin-dimm--ddr3-pc3-10600-6B8H.html

sapphire ati radeon hd 650mhz 5770 2gb
http://www.dabs.com/products/sapphire-technology-ati-radeon-5570-hd-650mhz-2gb-pci-express-hdmi-6ZQ7.html

520W 8CM fan
http://www.dabs.com/products/best-value-520w-grey-psu-8cm-fan-sata-5HMH.html

1.8m power cable
http://www.dabs.com/products/best-value-iec-5a-uk-mains-lead-1-8m--black-2WP0.html

acer 21.5” display
http://www.crescentelectronics.co.uk/acer-h223hqabmid-lcd-display-tft-215.html

microsoft keyboard + mouse
http://www.dabs.com/products/microsoft-business-hardware-pack-ps2-usb-41XL.html

150Mbps network usb adaptor with antenna
http://www.dabs.com/products/best-value-802-11n-wireless-usb-adapter---antenna-6M1J.html

samsung 1tb 3gb 32mb
http://www.dabs.com/products/samsung-1tb-spinpoint-f3-7200rpm-sata-3gb-s-32mb-65QC.html

lg 22x optical drive
http://www.dabs.com/products/lg-electronics-22-x-dvdrw-sata-blackbare---sw-5CXT.html

surge protector
http://www.dabs.com/products/belkin-6-way-economy-surge-protector-25LZ.html

My overall budget was £600 for everything (including monitor/keyboard/mouse) and my list totals to £574 (including VAT and postage). Thanks for any help.