slower shutter speeds will (IMO) always make a better picture. you get more action blur and sense of motion BUT they are also harder to get. the slower the shutter the better a photog you have to be. I never use anything more than 640 shutter speed for motorsports and usually shoot at around 160-250 for panning. aperture is also something to play with. for out of focus fore/background you'll want a lower # aperture (2.8 for example). this also allows more light when there isn't a lot of sun out. long lenses (i use 600mm and 400mm) help out but i don't recommend for the hobbyist(unless you have an extra $4-8k to burn). actually the 400 5.6 is a great "inexpensive" lens at around $1100. I would definatley recommend the 70-200 2.8 non IS ($1140) AND the 1.4 TC ($290)instead. The crop factor in the lower end digi's are pretty high (up to 1.6) so you can get good reach from a XT with 70-200 and a 1.4 attached (448mm). learn to pan and NOT prefocus on a area to shoot. todays DSLR focus are very good and you should be able to get good photos with the autofocus. if you prefocus and shoot at a specific area you'll get motion blur, but the background and track will be in focus and the moving object will be blurred. for a starting point, use the "sports" mode (high shutter speed) and when you master that move into TV mode and see how you do at different shutter speeds. hope it helps...