* Windows 7 or Windows 8? (No Apple!)
Windows 8.1 is presently horrible based on interface alone. but there is a fix patch coming in the next 2 months give or take. As of now, 7 hands down. in 3 months, we'll see. 64 bit OS either way. Apple sucks too.
* 8GB memory appears to be the standard, but I see models with up to 16 (or 32 for gaming machines). Do I need the 16, or is 8GB enough?
8 is likely enough. ram is dirt cheap though so adding more later is easy.
I have 32 GB and am contemplating swapping out for 64 GB. If you do alot of 3d model rendering it comes in handy. Certain games will also use it. No reason other than cost not to go higher.
* Any tips on processors and video cards? I don't really understand "dual-core" vs. "quad-core" or AMD vs. Nvidia.
Intel High end processors are better than AMD high end processors.
AMD high end processors are cheaper than Intel high end processors
At the mid range AMD is still cheaper, Intel still performs better, Intel processors will run somewhat cooler and more energy efficient due to smaller nanometer design.
A core I-5 Quad core 3.2 Ghz processor is probably fine for most gaming PC's. Make sure you match the socket type to the board
The Intel Core I-7 processors give you hyperthreading, which is basically virtual CPU cores (so a quad core becomes an Octo-core processor.
The Socket 2011 Intel processors are the most expensive, but you also get 8 dedicated ram slots with 4 ram channels. You pay a premium for that though.
I personally prefer Intel over AMD. I currently have a Hexacore I7 with hyperthreading (12 logical cores.
I prefer Nvidia over AMD specifically because Nvidia drivers are less annoying to install and maintain than AMD ones. Hardwarewise Nvidia wins at the high end currently, but that varies by month. Get what you are used to and prefer. Either will be fine for gaming.
* Is Alienware really worth the cost, or are you paying for the brand name?
No, and especially not since Dell bought them out. Now you are paying for a brand name on a Dell computer. There are other companies to try if you still want to buy high end pre-assembled.
* Any other tips would be much appreciated!
I'd like to keep the total cost under $1,000, which doesn't look like it will be all that difficult.
1. You want a Solid State hard drive (250GB minimum) to install the operating system and your most used games and programs on.
2. You want a paid of at least 1TB hard drives to install as a mirrored data array for your files
3. Pick a good, high end case. You will likely have it longer than any other component of your computer and it's the one piece that takes the longest to swap out. Start with a Cooler Master CM 690 III or a Cooler Master Haf X then branch out based off your design and look preferences. Large fans move more air with less noise.
4. Don't buy a cheap no name power supply, and always leave some room for hardware expansion (most graphic cards for gaming require at least 525 watts, I wouldn't put anything smaller than a 650 watt PSU into a gaming computer). Also make sure you get a modular power supply. Will make life easier for the build.
5. I prefer Asus motherboards, with Gigabyte as a second choice.
6. The case you buy will likely come with all the fans and screws you need. The motherboard will likely come with the cables. The CPU will come with a cooling fan unless you buy a socket 2011 Intel CPU in which case you will need to buy one separate.
7. Buy a tube of Artic Silver Thermal Grease to have on hand in case you need to take the CPU fan off and back on.
8. If you want I can put together a reccommended build list based on that budget. Does $1,000 include the operating system ~$100?