Plex Media Server Build - On Budget

Hi,

I am currently planning a Plex Media server build. I will be using this for running Plex Media Server on either Ubuntu or Win 8.1 (haven't decided yet). Apart from Plex i will be using this for light activities like browsing and running MS Office. I don't think I will be using more than 1 simultaneous trans-coding for Plex.

I have a Gigabit Ethernet at my home and will be hooking up this build to the router via the RJ45 cable connected to my router which is Linksys E3000. I will be accessing the transcoded feed via tablet - chromecast and phone through WiFi.

I already own a monitor, keyboard, mouse and speakers so I wont be needing any of those. Additionally I don't think I will be OverClocking the processor as this will be primarily used as a media server.

Here is my configuration:
Part list in pcpartpicker: http://pcpartpicker.com/p/VrdXdC
**CPU** - Intel Core i3-4150 3.5GHz Dual-Core Processor]
**Motherboard** - ASRock H97M Anniversary Micro ATX LGA1150 Motherboard
**Memory** - Kingston Fury Black Series 4GB (1 x 4GB) DDR3-1600 Memory
**Storage** - Kingston SSDNow V300 Series 60GB 2.5" Solid State Drive
**Power Supply** - Corsair Builder 430W 80+ Bronze Certified ATX Power Supply
**Case** - have not decided on yet on this can you please suggest a good case?

Alternate Configuration with AMD:
Part list in pcpartpicker: http://pcpartpicker.com/p/3QrCK8
**CPU** AMD FX-6300 3.5GHz 6-Core Processor
**Motherboard** - Asus M5A78L-M/USB3 Micro ATX AM3+ Motherboard
**Memory** - Kingston Fury Black Series 4GB (1 x 4GB) DDR3-1866 Memory
**Storage** - Western Digital WD Green 2TB 3.5" 5400RPM Internal Hard Drive
**Power Supply** - Corsair Builder 430W 80+ Bronze Certified ATX Power Supply
**Case** - have not decided on yet on this can you please suggest a good case?

Here are some of teh questions I have:

AMD Vs Intel: I know this questions has been beaten to death, but from all the articles I have read so far the suggestion has been that more cores = greater performance at least for Plex media server capabilities. But my question is if I have this system running 24x7 will the additional power consumed my AMD be drastically high? I mean even when the system is idle will AMD consume very high power? Also will the i3-4150 processor be capable of handling my requirement of 1-2 simultaneous transcoding?

SSD vs Hard Drive: I have chosen SSD to be my primary drive to host the OS. I will be adding WD Green 2TB drives to this build as my media collection grows. I am not sure if this helps or not, I plan to have this system running 24x7. So does having SSD vs WD green make any difference for the primary disk?

Ram: Does it make any difference if I use 2x2GB vs 1x4GB for the RAM?

Case: How important is it to have a case for this setup? I was originally planning on bolting the parts to a partition under my working desk. Is this feasible or would I be better of buying a case?

I am trying to target a build for under $350

Please comment on these builds