Kat,
I agree with Jonny regarding the mobo, sound and DVD drive. Since it would seem that the less you spend on this the better off you will be, I think onboard sound will be just fine, and SLI mobo is overkill and unnecessary at this point, I doubt you'll get the bang for your buck and SLI vid card installation can be as problematic as RAID'ing drives.
One optical drive (DVDRW) is reall all that is needed, if it won't install or run your games there is a problem with the drive or the software (in most cases).
With that being said, I hope all your parts arrive in working condition and your build goes without any screaming or bleeding.