The image handling for XMap is rather ill, at best. I recommend pre-warping your images using GDAL. It will take a little bit of time to learn how to use and get image quality settings to how you like them, but then when you import them into XMap, pre-registered, they look million times better.
Mike (Team Serious '10-'11)
Topo 6-9, XMap 6-7, SA '05-'09, PN Yellow, Orange, Blackse