Yeah that all looks good,
If you are going to be doing Digital Editting, then I would recommend getting a smallish hard drive for the system, and then getting a larger one for the data and things (digital editting takes up a lot of space)
Also you might want to look at getting a gfx card with VIVO or getting a dedicated VIVO card.
On the side of decent retailers, personally I would check komplett.co.uk first as they tend to have marginally lower prices, and they are a bit better on the shipping side of things, its a bit funny that as they ship everything from Oslo in Norway, but they seem to be better than quite a few of the UK retailers.
Dont forget that you will also need things like CD R/RW/ROM something like that or a DVD drive either ROM or writtable, if going for DVD Writeable then get the Sony DRW 500A (something like that)
You will also need things like floppy drive (cheapest is one from dabs.com)
Then also Monitor, keyboard, mouse, speakers and other things like that if you havent got them already.