I have been using a Logitech cordless keyboard and mouse for just over a year. I am hooked,the extra bells and whistles on the keyboard have been a boon and the versatility of using the arm of my armchair as a mouse mat makes life online really relaxed.
No free lunch though, the mouse eats AA batteries at the rate of two every 4/5 weeks and the keyboard uses up four of the same in about ten weeks. My computer is in use 8/10 hours per day six days per week.
I wouldn't go back to wires,no way.