You may want to hold off on the Creative X-Fi Xtreme Gamer 7.1 Soundcard. You can "try" the onboard first then if it's not up to par for you, you can always add a sound card. They have made great strides in the quality of the onboard audio. Check out the audio features your board comes with...it's quite extensive don't you agree?
Another tip may be to consider backing down from the OCZ 4GB (2 x 2GB). RAM is another easy upgrade down the road as need. I would suggest going with 2 X 1gb dimms first. 2gb dimms are very dense and if there is a problem, it's a very expensive one. Just get good RAM that will be available down the road so you can match them on the upgrade, should it happen.
So far we have have cut down some money so you can add another HD instead if you'd like.
no idea, i suppose the build... I will attempt to overclock if i have the time to spare to learn how to, its not on teh top of my to-do-list. I want the computer to last me 3 years at least, and i want to be able to upgrade parts in the future...