I have a RebelXT with a 28/300 Sigma lense that I use for taking pics of my kid playing softball.

I mainly use the Sports/action mode but as it gets twilight obviously it starts getting blurry.

I know I cant use the sports mode and take sequence pics anymore but what would be a good setting to start with and adjust from there?

I have had it for a few months and daytime shots are getting better and better but the twilight time even with the field lights is kicking my butt. I have tried a few different settings but nothing is working very well.

Thanks
Mike

Gotta up the ISO...

bumping ISO isn't always the answer. the first thing you can do is open the lens up all the way. make sure it's on its widest aperture, or the smallest f number. for you, this means between 4 and 5.6, i believe. second thing you can do, since you do have a ranging f/stop lens, is to take your photos with less of a lens length, such as shooting at 200mm instead of 300mm. this will allow you use a bigger f stop, to freeze action better. third thing to do is learn how to use motion to your advantage, such as panning. foruth, you can shoot with a flash. and then there's always upping the ISO. but shooting in Av will allow you to stop action better than sports mode. don't let your camera do all the work. I believe sports settings only use up to ISO 400 anyways.

... don't let your camera do all the work...

You know, that is probably the best piece of advice ever. I had read your post but then came back to it after a couple minutes once I realized just how powerful a statement that is. Thinking about it, the main ingredient to people improving their photography is coming to the realization that YES! Indeed they are smarter than the camera.