Just my 2 cents. I have been afraid of the sensor cleaning for a long time, but one day, after a hiking trip which included several lens changes in a rather dusty environment I had dirt on the sensor of my DS. The usual Rocket Blower cleaning didn't work.
I ended up doing a lot of reading about the issue and ended up with an Artist's Brush (from the local Michael's Store) and the Sensor Cleaning Kit from Micro Tools.
The Brush works 90 percent of the time. The few times when I still found a spec on my sensor (testing with MACRO lens on closest setting and smallest aperture pointed toward white background or sky) I used the wet cleaning method.
You are basically cleaning a glass filter in front of the sensor not the actual sensor. It does take a little practice, but after the second time it goes really easy. Always keep the camera on a tripod - that works really well during cleaning with the wet method.
Here a good link:
http://www.cleaningdigitalcameras.com/index.html