Yes, you could use GPUs if you are just playing. but really, ASIC based miners are really the way to go currently. If you can buy bitcoins you can buy ASIC miners at current prices, otherwise there is eBay. the 333 Kh/s Erupters are going for about $150 on eBay, about 1 BTC through group buys. Even they are considered expensive for what they do. you can see here what to expect from GPUs:
https://en.bitcoin.it/wiki/Mining_hardware_comparisonAny PC can host, the Raspberry Pi is just cheap to run. in your list, 16 gig is over kill, if the computer is only mining, 2 gig is plenty. If you run Linux, just about any SSD would do even 32 Gig is enough. Heck, an 8 gig USB stick would work.
When it comes to mining everyone is looking for ways to reduce cost because once you start mining the setup you have will make a little less roughtly every 10 days due to increase in difficulty. so if you don't keep increasing your hash rate you will fall behind. it is kind of a arms race. Cost of your Elec. is even a significant factor which is why people are giving up on GPUs. ASICs use very little Elec.
Also, most motherboards have sound on them no need for a sound card. MBs also network hardware built in. Intel i7 is over kill as well. A Celeron or AMD Semperon <sp> will do the job as well.
