advice needed on a new build

Guys (and girls)I need some advice on building a new machine as trying to decide on what to build is making beat my head against a wall, the problem stems from the fact that anything I build will be a considerable upgrade to what I am using at the moment.

The machine when built will used for a small amount of video editing, file serving films and music to other machines in the houshold and some gaming it also serves as my HTPC.

I was originaly looking at an I7-3820 based machine but different people have told me I should look at a ivy-bridge I5/I7 K based machine and one of my fiends keeps telling me to go for an AMD FX-8350.

Poss builds:

X79: M/Board Asus P9X79 PRO
CPU I7-3820 Cost=£430 + £55 NH-D14

Z77: M/Board Asus Sabertooth Z77
CPU Ivy-Bridge I7/I5 Cost=£405/£340

FX990: M/Board Asus Sabertooth FX990
CPU AMD FX-8350 cost=£300 (£340 with a better board)

For Graphics I will be keeping my gtx480 as most of my work/gaming is done at 1920x1080 but I will be adding another gtx480 at a later date (it may put out some heat but its cold at the moment and it can double as a space heater:p).

The memory would be either G.Skill Ripjaw Z or Corsair Vengance LP 1600 or 1833Mhz (16gb for the X79 and poss 8gb for the others).

I will be using my existing sound card.

For cooling the CPU I would use a Noctura NH-D14 for the 3820 or if I chose to use an Ivy-Bridge or an AMD setup I would stay stock for the moment and look at some sort of water or air cooling setup at a later date.

So the advice I need is which would be the best platform for me to use, is there any other motherboards I should look at in those platforms bearing in mind these are the highest boards I would go for ( I would go to the same cost as the Z77 board with the FX platform ), is there any other memory i should look at.

Thanks in advance.

So if I did decide to go down the Z77 route instead of a Sabertooth board another board i have looked at is the Asrock fatality pro board as I can get this board for about £125 or if I decided to stay with Asus I could look at a P8X77V-PRO instead.

Thanks again for any help.

Thanks for the replys. I will be more than likely going for the Z77 platform as whatever machine I build will have to serve me several years and I would like to leave myself an upgrade path with the GPU and take advantage of the newer cards advantages when I do change the card in about 2 to 3 years.

I have had a look at the Asrock extreme and Gigabyte boards and thay have given me something to think about, another board what has cought my eye is the MSI Z77 Mpower board what is the general concensus on this board is it any good as i can get this board for about £140.

Also should I look at getting the I5 3570K instead of the I7 3770K and save myself some money.