The main difference between micro ATX and ATX motherboards is the size, as you can see in this picture
I would suggest an ATX motherboard, as the GTX 770 is a quite big and long card, it also allows for more space between the CPU cooler, memory sticks. You get more cooling headroom and easier cable management.
About GTX 770 SLI, I think it's useless to power just one 1080p monitor, even a single GTX 770 may get bottlenecked by the monitor maximum fps of 60. As an example, I own a GTX 650, almost an entry level graphics card powering the main gaming monitor 1080p and a secondary monitor 1600x900 for web browsing while gaming, the GPU holds itself quite well during gaming, it runs War Thunder, planetside 2, Elder Scrolls Online (got beta tester invite) at 60 fps if you lower some settings, the point is, what can't a GTX 770 do?
If you do add another monitor, then it's more viable for heavy games. If you're thinking about a SLI down the road, better get a ATX motherboard, a PSU that outputs at least 500 watts, but 600 watts is preferable, to give the cards some headroom.
Here are two choices that I think are worthwhile:
http://pcpartpicker.com/part/asrock-motherboard-z77extreme3 Asrock Z77 Extreme 3 priced at $87 on Newegg.
It packs 4 3GB Sata ports and 2 6GB sata ports.
http://pcpartpicker.com/part/asrock-motherboard-z77extreme4 Asrock z77 Extreme 4 priced at $128 on Newegg.
It packs 4 3GB Sata ports and 4 6GB sata ports.
The sata port amount and PCI-e slots are the main difference between those motherboards, for the average joe, 2 sata ports are more than enough, the 3GB sata ports aren't that much slower.
About drives, are you planning on using a regular HDD to install windows and programs, or a small SSD and a HDD.
The latter being my configuration and I'm quite happy with the speed of the SSD, this SSD the Crucial M500 is a very good choice, it offers powerloss security measures, while being fast enough and not too pricey.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148693 priced at $70. While it looks a bit expensive, it's actually a very cheap one, comparing the competition and the speed is totally worth it! I installed windows 8 in 5 minutes flat, I used the phone chronometer to be sure.
Install windows and main programs on the SSD, and the junk on a regular HDD that you may have laying around.
Here's an updated build summary:
CPU: Intel Core i5-3350P 3.1GHz Quad-Core Processor ($177.98 @ SuperBiiz)
Motherboard: ASRock Z77 Extreme3 ATX LGA1155 Motherboard ($87.99 @ Newegg)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory ($79.99 @ Newegg)
Storage: Crucial M500 120GB 2.5" Solid State Disk ($69.99 @ Amazon)
Video Card: Asus GeForce GTX 770 2GB Video Card ($328.98 @ SuperBiiz)
Case: Antec GX500 ATX Mid Tower Case ($34.99 @ Newegg)
Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply ($44.99 @ Micro Center)
Operating System: Microsoft Windows 7 Professional SP1 (OEM) (64-bit) ($134.94 @ OutletPC)
Total: $959.85
It does go past the maximum budget of $900, but the SSD is really worth it, you can then buy a HDD later on.
You could try to build the computer with a computer case that you already own, you could shave off around $40 from the build. Imagine an old computer case running Crisis 3 on ultra 60 fps smooth! If you go that route, search guides though, as the size may not the enough for the big GTX 770.
Any dvd-rom unit can suffice to use CD's, you could also use one from another computer.
Enough writing, what is your opinion?