After much trawling of the forumns I went and brought a cheap secondhand Garmin Etrex Vista HCX, and I cant recomend it enough. It does everything I need like ground speed, altitude (barometric), distance, flight time and tons of other things. I use it to log all my flights and it only takes a minute to upload them all into Google Earth. It's also very compact and has good battey life. It's the only electronic thing I fly with.
Phil