Need some advice on sensor cleaning.

Hi guys,

I took some pictures last week and unforturnately it seemed the sensor of my 20D was getting dirty. See the sample pictures below. I have never cleaned my sensor before. I am not sure after cleaning if the result will be better than what it is now.

Do you think if it is worth cleaning now?

Here is the picture. The biggest dust on the left has gone after my rocket blower.

Here is the test I took at F16.

Here is the above picture after Auto Level.