If you're a gamer, Mac and Linux are not good choices. If you're wanting to play games, such as Crysis, at max settings you're going to need a very good PC to do it.
Case: This is largely an aesthetic thing. Get one that looks good for you. Remember, though, that newer graphics cards are large and will take up a great amount of space. I suggest getting an ATX full tower case. They're larger and heavier, but there is plenty of room to work and expand into. Cases made out of aluminum are more durable but often make more noise.
Motherboard: EVGA 750i is an excellent choice. It allows for the latest processors without the extreme costs of the 780i or 790i. The 750i allows for two nVidia cards to be linked in SLI whereas the 780i allows for three. The 790i is pretty much a 780i with DDR3 support which is far more expensive. If you want to SLI three cards, you're stuck with a 780i or a 790i.
Processor: Intel's Core 2 Quad lineup. Many newer games are making better use of the cores, I suggest getting a Q9300 or better, the 45nm technology will allow for cooler and more efficient processing. Plus, it's an excellent processor to overclock. The Quad-core processors are more expensive, they start at about $250, but they are more future-proof. You should also use good cooling with a higher-end processor, I suggest the Arctic Cooling Freezer 7 Pro or the Zalman CNPS9500 AT.
Memory: Get as much as you can, but remember, anything over 4GB will require a 64-bit OS to use. Your motherboard supports up to 8GB of RAM. Get your RAM from a good company such as Kingston or Corsair.
Power Supply: A 750W power supply will run most modern computers. A 1000W power supply is needed for people with triple SLI or many hard disks. Some also get 1000W to have a cushion for when they upgrade. A power supply from Corsair or Silverstone is of excellent quality plus they have a good warranty.
Optical Drives: I hear Lite-on drives are good choices.
Hard Disks: I typically get two, one for my operating system and applications, another for movies, music, and pictures.
Soundcards: The motherboard has a sound system integrated. However, if you want a better sounding solution, I suggest getting a soundcard. My personal favorite is the Asus Xonar D2 PCI soundcard. It is a pro-sumer card so it's more expensive, but it does sound really good and has plenty of connectors if you want to have a surround sound setup with Dolby support.
Graphics Cards: I suggest an nVidia GeForce 9800GTX if you're on a budget (when it comes to higher-end cards, anyway). If you're sort of on a budget and are willing to wait a month, go for the 9800GTX+ or the GeForce GTX 260. If money is no issue, go for the GeForce GTX 280. All of these cards allow you to SLI or link them together to make a very powerful graphics system. Keep in mind that to SLI you will need two or more cards. Remember, the 750i allows only for two cards to be linked whereas the 780i and the 790i allow for up to three. As for graphics card manufacturers, I go with EVGA for the warranty and their step-up program.
Operating System: This one can be difficult. Mac is ruled out since you pretty much have to buy a system built by Apple and have them install it. Linux is a good choice for a dual-boot system. Windows has almost all the games. Vista is more mature than it was and I strongly suggest using it. If you're going to get 4GB or more of RAM, you will need a 64-bit OS to use it all. Remember, there are some things you need to be aware of with 64-bit. First, is drivers. Only drivers that are for Vista 64-bit can be used. Almost every company that releases drivers for Vista has 64-bit compatible drivers, but there are rare exceptions. Also, some software may not run properly on 64-bit. Typically, most modern software will run just fine on Vista 64 but there are occasionally problems. I've been running Vista 64 for over a year and have only had one program refuse to work. Also, Vista 64 is more secure than the 32-bit variety. I suggest getting either Home Premium or Ultimate.
Edited by DJBPace07, 23 June 2008 - 06:28 PM.