That graphics card is a good call, it's brand new on the market (supporting technology that older cards won't), but it's not the uber-high-performance card which will cost $$$. I had written a long rant about why the card was overkill before I noticed it was a 5750 and not, as I had first read it, a 5850. Oooops.
I really don't think that you'll find that you are waiting for the hard drive in that build - certainly not to the extent you willbe right now! Windows 7 is better at optimising the disk to put the most frequently accessed data in the faster parts of the disk, and it will pre-fetch data that it thinks you will need too. Yes you could get faster, but not for the same price.
As for the sound card - it sounds like he's telling you the same as me, ie, overkill - in which case I'd save the hassle and moey, and get it yourself afterwards - it's not hard to fit the card, there's instructions all over the net if not in the manual for the card (it will be about 3 screws and that's it).
I'd ask if they can slow down the fan on the side of the case - you can usually get resistors to reduce the voltage that connect to the power plug for only a few dollars. If not, it's not the end of the world though - that graphics card won't generate too much heat compared to other similar performance cards.
All in all, that sounds pretty good, the shop clearly knows what they are talking about too. If you are looking to save some money to get the sound card in on budget too, I'd ask for a bump down in processor speed (that runs at 3.4GHz, whereas one running at 2.6 or 2.8 will be significantly cheaper, probably over $100), and maybe if you really need to, go for a smaller hard drive, though this won't save you an awful lot.
Ty - here's something to mess with your mind a little: http://www.techwarelabs.com/seagate_1-5tb-mod/ 10000rpm will only get you so far
Also, the 300GB Velocipraptors are faster than the 150GB ones, due to the increased data density.
