i5 box mainly for Video Editing (help required)

[Dodod]

First off I'm not looking for a gaming box, I'm looking mainly for home video editing (Videostudio Pro X4).

I've currently got a P4, 3.6 GHz, 3Mb RAM with an NVidia 9600 GSO. The kit is starting to get on my nerves as it seems to like the 100% mark an awful lot.

I've gone for an i5 2400 and might have been tempted for a 2500 (or even a K) but don't need the game (there's no such thing as a free game).

Now the questions (and I know there's no "best" or "right" answers):

What would be the best motherboard?

Is the graphics card I selected the right one?

If it's a "quiet" box then do I need to spend extra on an updated heatsink?

I also need a "Firewire" link for a video camera, do I just need a card or is it a feature on the motherboard that's more important?

I'm going to re-use three SATA drives (1x1Tb and 2x0.5Tb) as well as a BluRay Re-writer and DVD re-writer. Will the 500W PSU be enough?

Sorry for all the questions but I'm keen to get a decent box without buying a load of features I'll never use?"

After all of that, here's the spec:

Computer Case : Cooler Master Sileo 500 - Silent
CPU : Intel Core i5 2400 (4 x 3.1GHz) 6MB
CPU Heatsink : Arctic Cooling Freezer 7
Memory : 8 GB 1333 MHZ (2x4GB) - (DDR3)
Graphics Card : NVIDIA GeForce GT 430 - 1 GB - (EVGA) (PCI-E)
Motherboard : Gigabyte GA-Z68AP-D3 (Intel Z68)
Sound Card : Motherboard Integrated HD Sound
Networking : Motherboard Integrated Ethernet Lan (Broadband Ready)
Power Supply : Cooler Master 500W PSU - Low Noise

Many thanks for your help and suggestions.