Modular/fully-modular PSU for new build

Good afternoon fine OCN members

It's been a fair few years since I did my last build but with Ivy Bridge around the corner I'm considering my second build. First time around I went for a fairly beefy PSU [800w] thinking I might go crossfire, alas I never did. Although I do run a fair amount of drives and fans in this current machine I do think I could really downsize my power needs with this next build and plan on being a bit more conservative.

Although the build is obviously a couple months off I've started thinking PSU because I'm planning to get that first and do a bit of sleeving job on the cables. As far as spec its fairly rough as I wait for the details of IB:

IB CPU [TBD]
mATX mobo [TBD]
2x4GB DDR3 [will upgrade to 4x4GB in the future if I determine the need]
Blu-ray drive
SSD [either the Vertex 2 in my current machine or a new SATA3 drive depending on budget constraints]
Single GPU: ~7870 or Kepler equivalent depending on how price/performance turns out [no intentions of X-fire /SLI, cards are getting pretty expensive as it is and I think a single GPU should provide for most of my gaming needs at 1920 x 1200]

Possibilities:
2.5" or 3.5" drive for extra storage if needs be

As you can see it's a fairly lean build and I haven't yet decided on whether I will stick with air cooling and a decent HSF or try WC with something like a Crosair H80, space and noise will be the main considerations there.

I've had a quick go on the PSU calculators and was getting just under 500W recommended for a spec like that so I'm thinking I should be looking at a 550-650W supply and I want to go modular or fully-modular if possible to match with my limited spec.

So my main question is regarding getting a good reliable brand. Now around the time of my first build I remember reading a fair bit about how the Corsairs were good reliable PSUs but I've been doing some reading and I'm hearing the newer ones are not living up to the reputation that the former ones had earned? There seems to be so many brands and product segments nowadays that I'm a little lost on where to look, so any help and advice would be greatly appreciated.

TIA

Edit: sorry forgot to mention that I'm UK-based so some of the US brands are not available here

@Unorginal Sin: Sorry, forgot to mention those points - I'm in the UK and budget-wise I was hoping £100 max but I realise I don't want to get a cheap, shoddy PSU. You say 450W would be sufficient?

@Phibrizo: I'm having a look for the that in the UK, found this 500W version which is modular:

http://www.scan.co.uk/products/500w-psu-silverstone-sst-st50f-p-modular-85eff-80-plus-bronze-sli-crossfire-eps-12v-quiet-fan-atx-v2

@allikat: Checking those now, I did look at the Corsair first off but the price is a little high and then I read a few things about some of their new lines not being as good - any ideas which ones are still reliable?

Thanks for that info. I didn't realise that so many of these PSUs are actually rebrands from other makers. Is there some kind of list that you can look up which model it actually is or is it a sort of digging mission to find out what the original maker was?

Unoriginal Sin, I notice that two of the supplies you linked state having a single main 12V rail and the other 2 state having 4 x 12V rails. I remember reading that going for a single 12V rail was better is that still the case? or is it more a case of the base unit now?