2.2 is for Macs. PC monitors are usually "corrected" to 1.8 (I use the quotes because present day LCD/LED monitors are actually capable of linear response but, for comptibility reasons, warped to behave like analogic tubes).

I think that the best thing is to create a grey level ramp from pitch-black to pure-white and check that it appears to you uniform and that you can see it change uniformly.

Monitor setting have a profound effect: e.g. I have calibrated contrast and luminosity of  my Samsung 226BW LCD monitor the best I could with online tools and Vue tells me that my monitor gamma is roughly 2.0 (it should be more like 1.8).

GIMP 2.7.4, Inkscape 0.48, Genetica 3.6 Basic, FilterForge 3 Professional, Blender 2.61, SketchUp 8, PoserPro 2012, Vue 10 Infinite, World Machine 2.3, GeoControl 2