Do you really need a full tower case? I've got a nice (discontinued) Cooler Master mid tower that's huge. I know I wouldn't want anything bigger.
I'm a proponent of single rail PSU's. While it's not modular I and many others here run this one:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817703009 It's got more than enough power for your build and is a quality PSU.
I'd go with the eVGA mobo TilDeath posted (yes, I'm an eVGA guy too) and upgrade to 1066 memory (2x 2 Gb).
As far as the CPU goes you'll get better bang for the buck with an E8400 or E8500. If you're doing professional video editing then stick with the quad core.
Video card; get the eVGA 9800 GT (lifetime warranty with a 30 day step-up program).
Unless you already have the HD's get Seagates as they all have a 5 year warranty vs variable 3-5 year warranties on the WD's.
As TilDeath suggested, unless your old optical drive(s) are SATA just get (a) new one(s).
I's also take a good hard look at this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16829102006 It will totally unload all audio processing off the rest of the machine. As long as you're running XP there won't be any driver issues.
My 2 cents.