The Nikon D40x produces Image Quality a bit higher than Canon's mighty lightweight, notably in better noise control throughout the ISO range, and it has an ISO 3200 setting, which the XTi lacks. But the XTi remains a potent competitor, with faster and more sensitive AF using a sophisticated nine-point AF array that can track across the frame. The Canon takes a RAW file simultaneously with a highest-quality JPEG, not lowest. While we'd rate the build quality about equal, we'd trust the Canon more in dusty conditions, as it has both self-cleaning sensor and software dust deletion (the D40x, just the latter). And the Canon has no AF lens limitations -- all EF and EF-S lenses have built-in focusing motors.