Help with build

[kiraito]

Not sure if this is the right section to ask for advice, but I didn't see any other section for asking about builds in particular. Please move it if necessary.
I've been a computer enthusiast for quite a while but this is the first chance I get at building a PC.
Starting next week I'm going to start buying part to build my own computer, but it's my first time, so I fear of buying non-compatible or partially compatible parts, so I came here to ask if the parts in my build are alright, or if I could change some stuff. I'm not asking for advice in performance, my problem is mainly with cords and plugs, inputs and outputs, eg. I don't understand why cases have USB ports, I thought it was just a cover for everything else.
Will this be alright? Also, which case of the 2 I put is better? They are the same price.
As for the Power Supply, I don't know how much energy I need, so which version should I get?
Lastly, do I need a Wi-Fi antenna or can I connect to wireless internet with what I have in this list?
If you're wondering why I'm picking Audio Interface instead of Sound Card, it's because I'll be using this computer to record some stuff too.
Don't mind budget, since this isn't urgent and I'm going to be buying this parts over time.

MoBo: http://www.amazon.com/MSI-LGA1155-CrossFireX-Motherboard-Z77A-G41/dp/B008KW62WA/ref=sr_1_16?s=electronics&ie=UTF8&qid=1356573253&sr=1-16&keywords=msi+atx+motherboard

CPU: http://www.amazon.com/Intel-Core-i5-3570K-Quad-Core-Processor/dp/B007SZ0E1K/ref=sr_1_1?ie=UTF8&qid=1356570453&sr=8-1&keywords=intel+i5

Storage: http://www.tigerdirect.com/applications/searchtools/item-Details.asp?EdpNo=5250507&sku=I69-7010

RAM: http://www.amazon.com/Corsair-Vengeance-240-Pin-Platforms-CMZ8GX3M2A1600C9/dp/B004CRSM4I/ref=pd_sim_e_5

Power Supply: http://www.amazon.com/Cooler-Master-eXtreme-Supply-RS500-PCARD3-US/dp/B001G0WPLK/ref=pd_sim_e_1

Cooler: http://www.amazon.com/Cooler-Master-Hyper-212-RR-212E-20PK-R2/dp/B005O65JXI/ref=pd_sim_pc_2

GPU: http://www.amazon.com/EVGA-GeForce-2048MB-Graphics-02G-P4-2643-KR/dp/B0086UXQES/ref=sr_1_4?s=pc&srs=2529399011&ie=UTF8&qid=1356571395&sr=1-4&keywords=evga+video+card+2048mb

Audio Interface: http://www.amazon.com/gp/product/B002TTKI84/ref=olp_product_details?ie=UTF8&me=&seller=

For the cases, I have these:

http://www.amazon.com/Cooler-Master-HAF-922-RC-922M-KKN3-GP/dp/B0026FCI2U/ref=sr_1_10?ie=UTF8&qid=1356572273&sr=8-10&keywords=computer+case

http://www.amazon.com/Crafted-Series-Tower-Steel-Chassis/dp/B003WE9WQO/ref=sr_1_14?ie=UTF8&qid=1356572273&sr=8-14&keywords=computer+case

Will I need anything else?

Thanks in advance.

 

[AMD Radeon]

PSU is not good choice, pick one 500W-750W from corsair, antec, xfx, seasonic brand
http://pcpartpicker.com/part/xfx-power-supply-p1750bnlg9
this xfx 750 is my recommendation. cheap on sale

and GPU, dont get any DDR3 version. GT 650 1gb ddr5 is a minimum
i believe you dont play hardcore games, do you? so that gt 650 is enough

 

[kiraito]

What are the improvements of DDR5 GPU's over DDR3 ones?
I'm not hardcore graphics-wise, I'm more of an all around retro-gamer, MMO games player, and probably will be using Dolphin emulator at times, which is not that demanding. Will the 1GB be enough?

I'll suppose the parts will combine well since you didn't anything on that aspect.
Thanks for the tip on the Power Supply!