what aperture were you using? the flower doesn't look sharp. For macro shots try using the flash to control the light. It helps a lot. I don't remember if the Canon DR XT allows you to adjust the flash but it's a digicam so try out the different settings.
Here is one I took using my Nikon but I was using a 18-70mm at about 50mm or so (~75mm).
I didn't use the flash in this case but because the Sun was out I didn't really need to.
sorry for the size I don't have PS at work and this is the only size I have.
http://members.roadfly.com/dakar2m/wall/DSC_0012.jpg