For the record, that case is made by Antec and repackaged/sold Enermax, Chieftec, Alienware, and a ton others (Googlegear even has a "house" case that is the Antec case.
Second, make sure when you buy your mobo/memory what the best configuration is. Some mobos highly recommend you running paired memory. Also, like has been said, for gaming, cas2 is the way to go. Last I checked, Googlegear.com had a great deal on some 512MB cas2 Corsair XMS memory. Also, if you plan to ever do some overclocking, you might want to go with the DDR3500, that way, if you OC your fsb, you will also get some (albeit minimal) increase in your RAM performance as well.
Like has been said, a power supply is key. Just getting a 450w one doesn't always do the trick cuz of the way the power is distributed across the rail. Often, the 5v and the 3.5v (is that the right numbers?) share the same rail. The next power supply I get will either by an Enermax (which still shares the 5v/3.5v rail) or the Antec TruPower (which has a dedicated rail per each).
Vid card...I myself am going to move away from the nVidia and get an ATI Radeon AIW 9700 Pro in the very near future. Since this is the last vid card I get for a couple of years, I wanted the best (or rather, on generation back to save a little $$) so it will last.
Sound...If it is a key issue to you, get the Audigy2...you can't go wrong. If not, just use onboard. I have been using onboard sound for the past 6 months and it hasn't bothered me. Of course, I am also going to be getting an Audigy2 Platinum to go with my Radeon. Aren't tax returns great?
Case...you can get more than adequate ones for very cheap. Some good quality ones and sharp looking to boot would be the Lian Li or Coolermaster cases. Being aluminum, they are more cooling-efficient. And if you want space, the Lian Li 700 series (the server series) has more space than you can ever want.
Hard drive...I would go with one of the Western Digital 8MB cache ones. I saw a great deal on a 200GB one a week ago on techbargains.com . Would have got it but didn't have the room on the CC. You might want to opt for one bigger than 80. If you are going to sound mixing/recording, for good quality, that will take up a lot of space.
Hmm, I think that is all I have to say.