bah @ branded computers.
build your own beast.
Depending on your needs (casual/internet, medium/movies, heavy/serious gamer, et cetera), you will need to pay attention to a few items. If you go this route, here are my suggestions (what I will be doing, when the funds arrive, actually):
Motherboard
Intel -- LGA775 [last "generation"] | LGA1366 [newest]
AMD -- AM2? something. I do not prefer AMD, but that is just a preference (because I really never used them, and am waiting for bad intel to make a move...)
Either way, get one of the best motherboards, based on reviews online. I benchmark my markers for "best" by reviews on
Newegg.com - Computer Parts, PC Components, Laptop Computers, Digital Cameras and more!, by count/percentage/recent reviews. It is the foundation of your system, and can accommodate many different styles. This is a category you will not want to cheap out on. I prefer ASUS, but I have been peaking at Gigabyte as well, among some others.
Processor
Intel: [ LGA775 ] Core Duo @ 2.0 GHz or higher, Core Quad @ 2.5 GHz or higher.
Intel: [ LGA1366 ] Core i7 @ 2.0 GHz or higher. I am not sure if both dual|quad are under the i7 name.
AMD: Never shopped for AMD processors. See Motherboard, AMD note.s
This category you could do a litte pinching, knowing in the future you can upgrade when prices come down. In fact, Intel LGA775 processors should be dropping 2nd quarter 2009, maybe 3rd (LGA1366 processors just released to public about a month or so ago). The dual cores should be around 2.0 GHz, quads around 2.5 GHz. Strange proposal, eh? Well, quad cores are great for the games that require it, and if you get a higher clock speed, that is less work you may have to do if you overclock to "stay in the game." Dual cores are good for games, but are more suited for "less than" gaming.
Memory
This is the stuff that your running programs are stored in, besides an annoying technology called page files. When you open a program, a copy of the program is made from storage (usually hard drives or optical (CD/DVD) media, and stored into memory, then executed (run). The only leeway you will have with this component is the speeds of memory in the specification of memory that the motherboard supports (old: DDR; recent: DDR2; new: DDR3). These specs have speeds that correspond to how the computer operates at, and you should research the processor -- some older Intel ones only support some speeds, even if the motherboard officially supports higher; I am not sure about the newer Cores.
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Those are the three "basic" components, but there are other vital pieces as well. I literally just woke up, and I am not in the mood for thinking.