I don't know about specific Scan models, but they are another one of the "usual suspects" when it comes to audio PCs in the UK. You can check their standard systems and prices on their website, or spec up a custom build just as you can with the other suppliers.
Just for reference, when I was shopping for a new PC last year, I looked at all of the following:
Assuming they're all still out there, they all offer similar things at around the same price points. In the end I chose Inta because they worked out slightly cheaper than most of the others for what I wanted at the time, while still offering a build with decent components for audio work. As I mentioned earlier, the system I went for was very similar to the one you are looking at (I think it's an earlier rev/version of the motherboard in mine, but the rest of the spec is pretty much the same and it was at the same price). It's been absolutely fine, but I'm sure that most of the others would probably be OK too. They certainly all seem to get reasonable reviews in the press (although that could just be a normal case of magazines not wanting to say anything nasty I guess).
One other manufacturer that has recently returned to the audio PC game is Carillon. They might be worth a look as well, although I think they specialise more in rack-mounted systems. (They used to anyway.)
I'm surprised that no-one has popped up saying "build it yourself" yet. If you're confident doing that and can spare a little time, you can certainly save some money by going down that route. You could even take the spec of an Inta/DV/whoever machine as your guide and just buy the same components to put together yourself. I actually priced that up as an option, taking the Inta machine as my blueprint. I reckon I could have saved maybe 15-20% by going down the self-build route using the same components. However, as far as I was concerned, I preferred to pay them the extra and save myself a little time and hassle. Even though building a PC isn't exactly difficult, saving the time that I would have had to spend sourcing/ordering the parts, waiting for them all to arrive, putting them together and installing Windows was worth far more to me than a couple of hundred quid here or there. Also, if it breaks, I just phone them up and they'll sort out a repair or replacement, so it saves me even more time (and money) if anything goes wrong in the future. That's A-OK by me and I'll pay a little extra for that.