Gaming keyboard and mouse decision

Really depends on your budget. I am a fan of Razer products so I will link you what I think is best.

Keyboard- http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Mouse- http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Razer has great products for gaming. The cherry MX blues on the blackwidow just feel great when gaming. But then again, it depends on what type of feel you prefer on your keyboard.

The Deathadder is very comfortable and looks great as well. Long cable as you wanted to.

Again, it depends on your price range and what you are looking for:
Macro Keys
Backlit
LEDs
etc.

If you give more details on what you are looking for I'd be glad to help.

I would go with the Logitech G510 Keyboard and Razer Naga mouse if your playing MMOs

Depends on what you're playing.
Though if you need to ask a forum I'd hazard to guess that you don't really keep your finger on the pulse of mice.

So going away from the quality vs. value argument I'll just tell you the ones I enjoy.
Ergonomics: I have a friend that loves his vertical mouse, if you don't know what those are you can google it (he isn't a gamer)
MMO / Multifunctional: Logitech G600 MMO Mouse
FPS: Logitech G9

I haven't tried many mice for FPS other than inferior ones. Since I got the G9 mouse I haven't wanted to change because I feel uncomfortable playing an FPS with anything else. I used to use the Razer Naga, I hated the location of the "page back" and "page forward" buttons, logitech doesn't give the perfect solution for it but flapping between pages with the mousewheel is considerably more comfortable as well I personally feel the button layout is a lot more substantial in terms of tactility and help me recognize what keys I'm pressing before I press them.

As for ergonimic mice, the G9 and the G600 MMO Mouse won't do for an ergonimics enthusiast but if you're going for the pinnacle of ergonimics don't expect it to be playworthy.

Again, these are only my opinions, I'd strongly suggest you take a look at whatever mice tickle your fancy personally. I've been wanting to get a Cyborg RAT 9 Mouse for a while but I never really can be arsed to take the step and go out and buy it.

Good luck finding your mouse.

Oh and as for keyboards..
I'd go with the Logitech G710+ it's far more practical in terms of use, I personally think it looks better. The reason I'd pick it over the G510 is because of two reasons.
1. You never really look at the fancy screen that's on the G510, which seems to be it's only selling point.
2. On the G710+ you can press 26 keys simultaneously (G510 only has 5-key isolation)

The G710+ seems to be a pretty clear winner.

I second this combo, playing in MMOs is amazing with this combo.

PROS: The screen on the G510 works with tons of games, and has a lot of useful information like who's currently talking in vent or TS3. The programable keys are awesome if you are a macro fiend, and it really helps to have them. I use them a lot for raid leading macros and have separate keys for each raid marker icon. The mouse is awesome especially from a healing standpoint where you're moving really fast between healing targets while using the mouse to move. Really helps to eek out that next level in the gaming, for PVP content this is almost a must have, allows you to keep the mouse and have enough binding keys available to keep the keyboard available for strafing, etc.

CONS: The cost on this setup may be prohibitive, and it really takes a lot of adjustment to the new style of gaming.

To answer some of the other complaints: The "fancy screen" really comes in handy if you use it, it's a life-changer and one that you really don't think you'd use until you have it and then don't have it. "How did I play without it?" As to the 5-key isolation, I can see this becoming an issue in games with a lot more presses per second, but I have never personally ran into it playing Diablo, Skyrim, or various MMOs. You're mileage may vary if you play other games. The cords on my keyboard and mouse are more than adequate for me, and my tower is fairly removed from my seat/desk.

BUT: The TLDR version of this post is simple: go to a store that has them on display and try out the "feel" of the device, see how the weight of the mouse and the keys feel to press, then make your purchase where the price is the best.

Good Luck