After having used a Canon 20D for years, I have (have to have) planty of experience with sensor cleaning. Now the 40D is better, but it is not true, that it does not require cleaning, though not so often as the 20D.
The first important point is, that the blower does not help; sometimes the result is worse than before. The temptation is big, I started out many times with the blower, only to realize, that it did not help, in some cases it made things worse (not, that it matters, if one has to go wet). Canned, clean air might help, but that's dangerous (too cold and may contain some chemical), I never tried it.
I purchased Eclipse with the tiny cloth and sticks. Horrendeously, unashemedly expensive. However, the cloth pieces are really lint-free.
1. The cleanser: 99% (NOT 60%) isopropyl alcohol is perfect. It is POISON.
2. The tool: I cut and filed it from hard rubber (actually, from a leftover piece of bendable baseboard). Large enough to be held comfortably; hard enough to remove any dirt; too soft to cause any damage. The tip is a 1/4" wide, sharp edge.
3. The cloth gets wrapped on the tip of the rubber. Alcohol goes in some tiny cap. Tip with cloth into alcohol, not too much. The cloth *must not* be touched by hand. I have a pair of cotton gloves (good for handling the prints as well), I do not touch anything around with bare hands when cleaning the sensor.
The place: *never* in a carpeted room (rugs too are bad), nor in an office and alike, where there is much paper. These create tiny particles, which are always everywhere in the air. Ceramic tile floor is the best. Even a washroom can be good.
Clean with the tip around, watch the result: the alcohol looks like streaks, but it vaporizes in seconds, and then it must be free of steeaks (or the step has to be repeated).
4. Verification: first through a magnifier with light on it. If you don't see anything, it pays to make a test shot, white wall or clear sky etc. with aperture 22 or so.
If you see only tiny, not really dark spots, you can stop; they won't show up with larger aperture.
Important: the battery should be well charged, to prevent the mirror from shutting down during cleaning.
Of course, the best is to avoid (in reaity: to delay) all this. Do not change the lens in environment, where there are such particles. I go into the kitchen, or outside (rocky place, no dust) to change the lens, and always keep the camera with the lens mount downwards, while it is open. I remove the back cap from the replacement lens, remove the previous lens and immediately mount the replacement; the chamber is open only about three seconds long. Still, it gets dirty time and again.