I was on Amazon.com looking at the Logitech gaming mice and keyboards.

In particular, this keyboard:
http://www.amazon.com/Logitech-920-0022 ... CNQ4RANJ32

And this mouse:
http://www.amazon.com/gp/product/B002J9 ... B002J9GDXI

I've never owned a gaming mouse or keyboard before. So I am wondering what the benefits really are in gameplay. Starting off with the mouse, I can't recall what my Microsoft laser mouse DPI is but I'm sure it's nowhere near the 5700 of the Logitech gaming mouse above. How much difference does that really make say when playing a shooter? How does it affect gameplay? Is it easier to aim quickly and accurately? Does it help you to play better? There must be some reason people like them. I'd like to understand how beneficial they are. As for all the extra buttons I don't honestly see myself using them. Do people really find all those buttons on a mouse helpful? What for? What do people activate with them?

On to the Logitech gaming keyboards. The one I linked above I think is their entry level model. I like the backlit keys feature. That is pretty cool. Some of the other stuff seems pretty useless to me personally. The defining feature of this keyboard really seems to be the macro keys. So the question is, what are they good for? I'm trying to imagine what I'd want to macro in a shooter for example. What would I want to macro playing some RPG? What would I want to macro playing World of Warcraft? Once again, people like these a lot for some reason but I am honestly clueless about what specifically it is. So please enlighten the clueless!

Thanks a lot for any feedback on this stuff. I appreciate it.

I don't game, but you don't need to game to benefit from the Logitech G500 Programmable Gaming Mouse. Just get it. It materially improves the computer use experience.

I don't play fast shooters, but I do play games. The biggest effect on accuracy for me was getting the frame rate high enough. If the game stutters you can't hit anything.
I used the Logitech MX518 for a while. I never got to liking it but didn't know why. Then I bought a 10€ laser mouse with 1000 dpi at the local electronic store. I've been using it ever since because it's much more comfortable for me, probably because it's bigger and the shape just fits better in my hand. I think the better shape leads to more controlled movement. I like the higher dpi because I don't have to drag the mouse too far, but 1000 dpi is enough for me. I would put comfort and ergonomics first, performance and features second.
I also have a Nostromo. You can use macros, but I was too lazy to program it to anything but WASD. I don't use it anymore either. If you use macros in games now, maybe through LUA scripts, you might give a gaming keyboard a try.
All gaming centric accessories I used were underwhelming.
If ask your question on a gaming site you might get a totally different answer.

A simple Logitech RX250 (with the weight removed) is my weapon of choice. Never liked the "gaming" mice very much. Depends on the game and the style of the player I guess.