Imho, not bad at all. Seems you have done and will continue to do your homework and not be spoonfed simple answers to simple questions. Right on
If you are near a Micro Center retail store, you can purchase a 3570K & mobo combo at a $50 discount. It's a good deal actually. The Gigabyte you selected is a solid choice, and if you are partial to the brand, that board should serve you well.
The 3570K is probably the best all around gaming CPU for the money right now.
It's probably not a good idea to mix RAM, so I'd suggest going with a new set. If I'm not mistaken, Photoshop and Maya will benefit from the added RAM, so go with a 16 GB kit (8 GB x 2 sticks) of RAM similar to the one you've selected. For gaming though, 8 GB is all you need.
The Radeon 7870 GPU is a solid bang-for-buck gaming card right now. You'll get mid to high settings at 1080 resolution with new games no problem.
ASUS or Samsung optical I think matters little.
PSU - one of these or similar will suit your build methinks:http://www.newegg.com/Product/Product.a ... 6817151094http://www.newegg.com/Product/Product.a ... 6817139028http://www.newegg.com/Product/Product.a ... 6817371044
If you are set on RAID, then imho the lowest cost per GB drive may be a good option. Lately, that goes to the Seagate Barracuda - the Egg prices are:
1 TB = $70
1.5 TB = $80
2 TB = $100
But if your current HDD is in good working order, there shouldn't be a problem with using that. You can even use your old HDD along with a new HDD in a RAID 1 setup. I don't know the details, but performance does suffer when drives in RAID are not identical so that may not be a good option. My point is, your old drive probably has a decent lifespan left in it (two years isn't that long) and it would be a little wasteful if it was not utilized.
You should be able to transfer your Windows 7 to your new build with a telephone call.
Also, I'd suggest adding a CPU cooler since the stock i5-3570K fan runs hot. The Cooler Master Hyper 212 Plus or Evo is another one of them best bang-for-buck parts for about $30. The Plus is only $20 after rebate on the Egg right now:http://www.newegg.com/Product/Product.a ... 6835103065