I hope the following information may be helpful to ebay customers who intend to purchase a new sd card for their tomtom rider. I recently purchased a set of european maps for my rider and these need a 2gb sd card as the original card supplied with the unit is not large enough.
I duly purchased a sandisk 2gb card from a reputable ebay company but found that the card would not work with the Tomtom no matter how hard I tried. Please be assured that there was no fault with the sandisk card other than it wouldn't work with my tomtom rider, it works fine with my camcorder.
Tomtom support was not really helpful and it was due to the kind advice of another ebayer that I solved the problem.
It is important to but the correct card for the tomtom and the one I eventually found was a basic Kingston 2gb sd card which are vailable for about £45.00 on ebay.
Unfortunately Tomtom don't seem to state that their units are incompatible with some brands of sd cards and the best advice I can give is check with the seller first that the card will work with Tomtom products.