I've heard Logitech has taken the lead from Klisch in PC sound lately. They have such a wide variety of speakers, and there are nice 5.1 setups in all kinds of price ranges. I'd recommend looking for a midrange 5.1 Logitech setup rather than a 2.1 Klisch setup.
On the case, I recommend getting a nice one (mine sucks, and i'm probably getting a new one) but $271 seems awful steep. I'm looking at a Thermaltake Tsunami tower for $105, those seem pretty cool. All in all, I'd look for front/top usbs, solid construction, a window, and front and rear 120mm fans, but that's just me.
Oh, and about the hard drive, I had a DM10 and i liked it, but there were compatibility issues with the NF4 chipset. I don't know who's fault it is, but i can't test it cause i've already RMA'd it. I think there is new firmware for the HDD, and new BIOS for most NF4 mobos, so i'm guessing one of them has fixed the problem. I'd recommend it over the raptor for the price and larger storage, but a raptor is still a bit faster, and if you find a good deal on one (i.e. $150 or less) then go for it. Otherwise, there are plenty of cheap deals on slickdeals for regular SATAs.