Just a few things i'd suggest:
The disk drive you've selected is the retail version, but the OEM would be fine and save a couple of quid:
http://www.scan.co.uk/products/lg-gh...sata-black-oem
Or just get the cheapest Scan has, they're all basically the same feature-wise at this price:
http://www.scan.co.uk/products/samsu...sata-black-oem
The WD Caviar Greens are their low-power models. I know you're getting an SSD, but you'd be better going for a standard speed 1TB drive as well, like:
http://www.scan.co.uk/products/1tb-s...he-8ms-ncq-oem
Which is also ever so slightly cheaper.
The MSI motherboard's good, but i'd compare it to the Gigabyte D3H. Have a look at reviews, they're both good boards but Gigabytes of late have had pretty glittering verdicts.
http://www.scan.co.uk/products/gigab...dvi-d-hdmi-atx
The graphics are good for the money, just be aware that XFX have a sketchy record for customer services and returns.
Does the PSU have to be modular? There are better power supplies in that price-range (Seasonic are generally the best built you can get, but they're often re-sold by other manufacturers - XFX, select Corsairs, Antec), and 650W is perhaps a little more power than you need, but just looking at that rating for now i'd suggest instead of the OCZ:
Non-Modular:
http://www.scan.co.uk/products/650w-...12v-fan-atx-v2
- Or -
http://www.scan.co.uk/products/650w-...uiet-fan-atx-v
Modular:
http://www.scan.co.uk/products/650w-...ingle-rail-psu
- Or -
http://www.scan.co.uk/products/620w-...-quiet-fan-psu
These are all Seasonic built and very reliable because of it. I was faced with similar choices lately, and i personally went for the Corsair i've linked you to (if it matters at all).
Unfortunately the modular are out of stock, but the non are in. You could call Scan and ask about when they're likely to be back in stock, but given the choice i'd just go non and save a few quid anyway.
Taking all of the above into account, you're left with roughly the same cost as you started with.