I'm going to attempt building a system for the first time ever and was wondering if you could give me some info on whether there'd be any problems on the parts I'm going for and if its underpowered/overpowered in any regard.
DDR2-1066 will be of value, only if you need maximum overclocks. DDR2-800 will be less troublesome otherwise. Also note that the Corsair dominator designation just gives you a fancier heat sink which is not really needed.
I would defer on the sound card. Onboard HD sound is very good these days, and you could always add one later. Also, sound card drivers seem to be very troublesome.
Would a wireless router be better than a card? What is it for?