Thanks for the replies. I think i've sorted it, or at least identied the problem. I'm using the 1.5g ouput however when I move the sensor, the trace on the scope a mixture of static and dynamic errors. Therefore, when i hold the sensor in my hand the vibrations from my hand 'shaking' were causing dynamic changes what looked like a 'noisy' signal, infact its just the accelerometer being too sensitive. I held the sensor in a clamp and moved it, thus damping out the vibrations (dynamic motion from my shaky hands) and the output was smooth, linear and as per the spec (within reason). Problem is, this doesnt help me, as I'm only interested in displaying an angle, ie static output, therefore if the sensor is on a vibrating vehicle for example it will be displaying the rate of acceleration due to vibrations, rather than 'at rest' static angle.
Hmm....back to drawing board.