Nothing else really needs changing. The Antec Earthwatts 650 £62 is a bit cheaper, still 'overkill' for one 5770, but I suppose it's nice to have a PSU that can support a lot of single graphics cards. So you have some options for upgrading the video card in the future.
This one is also a bit too good to pass up and is actually a 650W PSU: Silverpower SP-SS650 £66
I'd prefer these cases over the one you linked:
Thermaltake Armor A90
Antec Nine Hundred (Antec 900)
Lancool Dragon Lord PC-K62
Coolermaster HAF 922
Antec Nine Hundred Two (Antec 900 Two)
Partly as they are bottom-mounted PSU cases, so they don't have to draw hot air in from the rest of the case. The HAF 922 and Antec 900/902 are amongst the best cases for cooling the components. And partly coz my choice/taste in case might be a bit different to yours.
Thanks for the answer, was beginning to think all hope was lost The 1TB hard-drive looks great and I'll check the cases, but I really like the one I picked, it's shiny and has flappy paddles (I'm easily amused). As for the PSU thing, according to this review (http://www.hardcoreware.net/reviews/review-280-4.htm) it counters it with an exhaust fan, but I don't really know much about that.