CPUs and GFX cards +random qs :), transcoding 1080p

What processor would be best for HD-transcoding and use in a hackintosh box?
* Intel is probably preferred as I am looking for something that works nicely with Mac
* Will my S1283-HDT cooler work on an LGA-1156 board? Doesn't look like it

Also, why is the mobo recommended in two of the new build recs mATX? What is the disadvantages/advantages of mATX?
Are there any other mobos that I could look at that will give a flawless and easy install?

What cpu cooler could i look at, i currently use the s1283-hdt but i dont think it supports lga1156, so if i get an lga1156 processor what should i get? the mungen-2 isn't widely available in Victoria, so other suggestions are good. I was thinking maybe the tx3?
cooler master.com/product.php?product_id=6602

What gfx card would be recommended, ideally cheaper than the 9800gt - which is why i am asking, otherwise i would just choose the 9800gt.

One thing that is important to me, even though it is hard to predict, is how supported the parts will be in 2 years so i can still update

Lastly, is an ide dvd-rw okay? I read that SATA is better - is this right? Is it worth an upgrade?

Apologies to anyone who sees this twice - prefer more information than less.

Help would be awesome! Thanks so much