The motherboard has an integrated sound chip. So the sound is actually built into the motherboard, eliminating the need for a separate sound card.
The burner you listed is just a CD burner and will only read and burn CDs. The one I posted is a combination DVD and CD burner that can read and write to both CDs and DVDs. Many of today's new games come on DVD and you could also watch DVD movies.
A 1TB drive isn't completely necessary. You could get a nice 640GB drive such as the Western Digital Caviar Green WD6400AACS 640GB
for $69.99 and save yourself another $30.
The Acer 22" LCD monitor is a really nice deal at only $159.99.