For my money I am very happy with:
Logitech Wave Pro Desktop Black USB 2.4 GHz Wireless Keyboard & Mouse Combo
The mouse is excellent with adjustable dpi sensitivity by a button on the mouse. The mouse is rechargable by USB that comes with an ac adapter so it may be recharged from an outlet when the PC is off. I didn't even bother to install the logitech software that opens up other features. The keyboard is the best I have used by far -- much quieter than previous keyboards -- I hunt and peck and really pound the keyboard, but this one feels very smooth and is very quiet.
My gaming is limited to mostly 3rd person games -- not fast paced shooters. That said I have never noticed any lag. It runs on the pricey side but is worth it.
The only thing you might want to do is purchase a
USB cable extension so you can have the 2.4 GHz receiver close by. I need the extension when use my HDTV for Games and movies.
