Mobo: Gigabyte, all the way. GA-Z77X-UD3H is great, cheap, and OOB mac compatible
CPU: If it's for editing, go i7, pick your poison. If not, go for an i5, the 3570K is nice
Cooler: Cooler Master 212 Evo, nice and cold
GPU: This depends. If he needs a graphics card, the gtx 650 or 660 (MSI, Gigabyte, EVGA, etc.) will be good for $1000. If he doesnt need it, stick with the integrated graphics
RAM: Depends again. 8GB for non-editing/gaming purposes, 16 for editing, 32 for after effects and animating
PSU: Corsair CX series, 600W. Quiet, efficient, enough power
HDD: Depends on his needs. 1TB is usually enough. If he can afford it, buy an MSATA SSD for the booting (32GB)
Case: Check out the 230t by corsair, sexy small case.
Hope it helps!