You will need a fast shutter speed to avoid shake with the 70-200 f/4, not really heavy like the f/2.8, but still needs to be kept steady to avoid blurring. Think something along the lines of at least equal to the focal length used and then include the crop factor of 1.6
Would suggest you take it off auto iso (unless you can set a maximum, know the 550D can) as well otherwise the camera will bump that right up to get the desired speed which will introduce noise
If you are pointing and shooting which I assume to mean you use the camera on auto rather than one of the other settings the ability to cancel auto iso is probably removed along with some other functions
My daughter has a Canon 50-250mm IS which produces great results at a bargain price,the new Tamron 70-300 VC gets good reviews too.
The 70-200 f/4 IS has two stage stabilisation, one setting for normal and the other for panning, makes a difference and although costlier can mean many more keepers
Suppose all this is rather academic now though if you have made your mind up and bought it