The i5's are good chips but only 2 cores + 2 Hyperthreads. The i7 has the 4 + 4 so if your Movie making is anything like video conversion and is very processor intensive then you will want the extra cores, especially if you're like me and do other things while it's compiling in the background. Gaming has yet to use 4 cores so that won't enter into the picture for awhile.
As far as the video card is concerned if you're going with the ASUS P7P55D-E Pro board then it only supports 1 video card at the X16 lane so no matter which card you get make it a good one. I like the ATI & Sapphire cards myself, They have never given me trouble.
As far as the memory goes I would stick with the 2 X 2GB pairs since the board and processor only support Dual channel. These look like they will work fine as long as your processor speed is at lease 2.8GHz, Mushkin 996657. You can
get them here for only $159 and they are the 1600MHz with latency timmings of 7-7-7-20 at that speed.
If you need the win 7 pro 64bit it looks like you can
get it here for only $85. It's an OEM version that's why the price is so cheap.
You can get the Sapphire Radeon HD 6870 1 GB GDDR5 at Newegg for only $255 and this card ought to hold you for quite a while.
So that makes -
Rosewill Challenger mid-Tower Case from
Newegg For $55
ASUS P7P55D-E Pro from
Newegg for $180
i-5 760 (i-7 a better choice for future proofing?) I would go with this processor - Intel Core i7-870 Lynnfield 2.93GHz 8MB L3 Cache LGA 1156 95W Quad-Core Processor BX80605I7870 from
Newegg for $280
DDR3 RAM 2 x 4GB 1600 mHz (considering 1333 and/or 2 x 2 GB) These look good and will work on your motherboard
Mushkin 996657 XP 4GB (2 x 2GB) for $159
WD Caviar Black 1 TB 7200 RPM 6.0 Gb/s from
Newegg for $90
5770 1 GB video card (would eventually like a triple monitor Eyefinity set up)You might like this card instead, it's the SAPPHIRE 100314SR Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity for only
$255 from Newegg
Antec Earthwatts 650W PSU from
newegg for $70
Win7 Pro
from here for $85
And that gives us an approx. total of $1,175. Puts us inside your price range and you shouldn't have to think about upgrades for awhile.