Radiator(s) - you need at least a 120.4 or equivalent in seperate rads for an i7 and a high end gpu. black ice SR1 is the rad of choice at the moment.
Fans - depends on your rad really but gentle typhoons work great on an SR1
Pump(s) a single D5 will do the job, my entire loop is powered off one, dont need anything else but consider a nice top for it to make mounting, fittings and flow directions easier.
CPU block, any of the EK supreme range will do. there really isnt much in it although many would have you believe otherwise.
GPU block(s) again, i use EK blocks, full cover if you plan on keeping the card a few years. dont bother doing your gpu if you upgrade every year.
GPU backplate(s) (optional, I believe) totally optional, only for aesthetics but look brilliant.
Tubing. depends on preference. personally i like 7/16 as its a nice size and most brands have a good bend radius.
Fittings, be they barbs or compression fittings
you need two fittings for each component in the loop. compression fittings are rubbish unless you spend a lot of money on them, my advice is to get some nice fatboy or Dtek style 1/2 barbs to match the tubing i mentioned above.
Distilled or Ionised water are the preferred coolants (Colour dye is optional)