first try with selective colour

[cosmonaut]

Here is a fast way. First go to the channel pallete and pick the best channel, red, green or blue. Then open channel mixer use the drop down and select the color, then click mono chrome box on the lower left. Then go to the channel mixer layer, select eraser and erase the area you want. I find this the fastest. If you choose the strongest color in channel mixer to convert to B&W you will get a much better conversion.
Cosmo

 

[tpe]

Use of layers is a very good habbit to get into as said a couple of times, if you make a mistake it makes it so much easier to fix. Cosmonaut is also onto a good thing, use of the coulour channels gives a much better convertion, and there are a million ways to convert to b&w and desaturation is generally the worst.

If you are not scared of layers make a new one, fill it with a solid grey fill, turn the blending mode to saturation. This makes the image b&w. Then adjust the colour of the layer below and effectivly get a complete b&w filter set. Try changing the contrast for each channel individually, it opens up a whole new world. Incedently it also makes it much easier making masks if you change the contrast in the channel that most represents (ie the red for the sofa) the thing that you want to make a mask for, then you can use the majicwant and turn it into a quickmask by clicking on the little round circle and square icon under the colour swatches on the tool pannel.

tim