tdgeek: This seems ok
http://www.torpedo7.co.nz/products/5ACUWN4V2/title/alpha-vss-235-wireless-cycle-computer-w-cadence
Wired or wireless? Are they all easy to fit?
Definitely go wireless, they are easy to fit. You can also get Bluetooth sensors so you can use your phone as the computer. There are some good apps as well for tracking rides etc.
If you want information about calorie burn you really need a heart rate sensor. They are also good for monitoring your fitness levels etc as well.
The other option if you do want heart rate monitoring is a gps watch but they get up there in price.