Accuracy of Wii Fit Scale?

There is a five pound discrepancy between my bathroom scale (229 lb) and my Wii Fit balance board (234). I put a 10 pound weight on each and both were accurate.

I'm new to this and trying not to focus on the scale too much and just do what I need to do, but it would be nice to know what weight I'm really starting at, so I can more accurately set my goals, etc.

Anybody have any experience with the Wii Fit balance board? Which scale should I go with for more accuracy?