I don't know if someone's said this before, but I don't care, I'm saying it anyway:
If you're a competitive gamer like myself, you're going to need a good mouse, a good mousepad, and a good pair of headphones or a good headset. The keyboard shouldn't matter too much, as long as it clicks fast and is comfortable for you.
Mouse: If you're going to be using high resolutions (1600x1200) and high sensitivities, get a mouse with a high DPI, like the Logitech MX518 (what I have). Some people think it's an oddly shaped "alien mouse", but it's all down to personal preference. If you are going to be using high resolutions and high sensitivities, and you don't like the MX518's look, you might want to check out the Razer Diamondback.
However, if you are going to be playing at lower resolutions, and with a low-medium sensitivity, then you should look at the Logitech MX300 or MX310, or some of the Microsoft mice, whichever one you prefer the shape of. 1600 DPI is really overrated, TBH. There are gamers like Cooller (the Russian dude who just won the Quake III Tournament at ESWC) who use a Microsoft Wheel Mouse Optical 1.1A USB, and his aim is godly. Seriously.
Logitech MX518: http://www.newegg.com/Product/Produc...82E16826104178
Razer Diamondback: http://www.newegg.com/Product/Produc...82E16826153103
As for headphones, it depends on what you're going to be playing, and where you're going to be playing. If you're going to be playing team games, you're going to want a headset. If you're going to be playing deathmatch games, you're going to want a nice set of Sennheisers, although a good headset will do fine as well, you'll just have to wear it with the microphone up, and generally headsets aren't as good as headphones, but they're more convenient.
The best headset I see out right now are the Icemat Siberias. Everyone says they're extremely comfortable, that they hear things a lot better when they wear them, and that they're just a good pair overall. However, they are a bit pricy. If you go to LANs, though, these things are kickass. Why, might you ask? Because they have a USB soundcard that you can use, so that even if you're not using the computer you normally use, you're going to get the same sound on ANY computer. Also, the headphones look like they're pretty good at blocking out outside sound, which is a major plus for LANs.
As for headphones, a very good pair for LANs, and the pair what I have, are the Sennheiser HD-280 Pros. The bass on these headphones is amazing, and I can barely hear anything people are saying when I wear them, which is another plus. They're comfortable, and the sound quality is just rape. However, they're also a bit pricy.
If you're on a budget, here's a link to the headset I used for a very long time, and it is by far the best I have ever used for the price:
They're about 13$, and they just own. I still wear them around my neck if I'm playing CS, so I can use the microphone.
Lastly, mousepads. I'm not gonna recommend a hard surface mousepad because I've never used one, nor do I want to use one. To me, they just suck. Why? Because,
1. They cost too damn much.
2. To get the most out of them, you have to use them with Hyperglidez or Mouse Skatez (teflon mouse tape), that wears down and changes your accuracy constantly.
3. They're usually too small in size.
However, if you are interested in hard surfaces, I hear the Razer Exactmat is very nice, and that Steelpad surfaces are also very good.
As for cloth pads, I use them because:
1. They don't cost so damn much.
2. You don't have to use Mouse Skatez or teflon tape, and if you do, they don't wear out as quickly.
3. You always have more than enough room to move your mouse, so you can mess with your sensitivity more. Lower sensitivities are usually more accurate, but higher sensitivities allow you to do 180s a lot quicker, and just do more things in general.
4. They're more consistent. You don't have mouse tape that's wearing down, constantly changing how fast you use your mouse.
For cloth pads, I'd get either a Fatal1ty pad (Fatpad) or a QcK+. I use a DKT pad, and it's mad nice, but I can't find anywhere to buy it.
is where you can get the QcK+, and Fatal1ty.com is where you can get his mousepad. Btw, incase you haven't heard of him, he's pretty much the #1 PC Gamer in the world.
I can't believe I just wrote all this, but whatev, I hope someone benefits from it.