Spec for new PC advice needed urgently

I am trying to put together a spec for a new computer. Need to finalise it quickly now because of VAT rise and my 8 yr old computer keeps crashing.

Wanted to keep price down but it has risen, of course.

Mostly for photo editing, some low end games. Hoping to get hold of my brothers HD camcorder at some point, so may do some video editing.

Also want to use it to save TV programmes occasionally if several things on at once.

I want wireless capabilities, as at moment have to run long cable to hook up to telephone.

Do want to run 2 monitors eventually. At the moment just got old CRT, but am going to get digital, so if old monitor doesn’t break down, would like to connect it as well, when old computer crashes permanently.

Got a new Digital TV so may want to link it up, don’t know yet.

So far : Price £729.68 inc VAT

Cyberpowers systems UK

Case: Coolermaster Elite 310 mid tower case (43cm?)
CPU: Intel Core i5 760 8GHZ 8MB LGA1156

Motherboard: Asus P7H55-M Intel H55 chipset DDR3 LGA1156 mATX w/Onboard Graphic, HDMI, 7.1 HD Audio, GbLAN, HDMI, USB2.0, SATA-II, 1 Gen2 PCIe 16x & 2 PCI-e, 1x PCI

Memory: 4GB (2x2GB) PC10666 DDR3/1333mhz Dual Channel

Video Card: Nvidia GeForce GT 460 1GB 16X PCI Express

Power Supply: 450 watt Dual Rail Quiet Power supply

Hard Drive: 1TB Samsung Spinpoint F3 SATA-II 3.0Gb/s 16M Cache 7200RPM

Data Hard Drive: 1TB Sata-II 3.0Gb/s 16M Cache 7200RPM
(internal back up for my photos, I will have an external one as well)

Optical Drive: 24x Double layer dual format DVD+ -R + RW + CD-R/RW Drive

Sound: High Def on-board 7.1 Audio

Network: onboard 10/100 Network Card

Wireless 802.11B/G Network Card: PCI-E Wireless 802.11g 150Mbps, Network Interface Card

Flashmedia Reader Writer: Internal 52in1

Operating Systen: Windows 7 Home Premium
Software: Works 9

Media Centre Remote & TV Tuner: Media Centre Remote Conrol + Hybrid PCI Digital TV Tuner

Question: Is micro motherboard OK, read somewhere that full size motherboards better for airflow and if need to add things in future?

Also there are H55 and P55 (£5 dearer) What is difference?

i.e. Motherboard: Asus P7P55-M Intel P55 chipset DDR3 ATX Mainboard w7.1 HD Audio, GbLAN, USB2.0, SATA-II Raid, 1 Gen2 PCIe, 2 PCIe x1 & 1 PCI.

Seems to be full size but doesn’t mention on board graphics and HDMI not mentioned, H55 had it twice.

(Note: Asus seems popular with this company)

Memory: Is 4 GB Ok, my nephew said I should get 8gb, but do I need it for photo editing? An extra £38 I believe.

Video Card: Nvidia GT 430 Is this a good card for photo editing?

Importantly, is it the motherboard or the video card that the monitors connect to: are these suitable for 2 monitors?

Network Card: onboard 10/100 Network Card
OR Network: onboard 10/100/1000 Network Card ?

Thanks for any help for these last few queries. I don't want to get too technical or massive changes as I've already spent months trying to get my head around these things.

I am hoping that the new computer will last as long as the old one.