Forum Moderators: not2easy
You could use the Magic Wand tool to pick out the different colours in the logo and change them to white. Unless they are very simple blocks of colour, this might not be too accurate, however.
Another way to do this with indistinct colours and gradients is to make a copy of the image on top of the original. Change the contrast as high as it will go on the top image (using whatever Photoshop control works this - in Fireworks it is a slider on the color effects) so that the logo is now all white. Use the lasso tool (or whatever its equivalent is in Photoshop) to eliminate the surround and leave the white logo on top of the untouched surround behind.
This will swing your decsion on how best to edit it. If it is a vector image you may well be able to edit the colours in a package like illustrator or freehand. If it is a raster (jpeg gif bitmap etc) then you will need to carefully edit the text using the selection tools. It's quite hard to give advice without seeing the image and how the text is aliased, font sizes etc but I would try and avoid the second option. Not just difficult but non scalable logos are a nightmare if you need different versions, instances, sizes, quality etc....
<added>a second behind you steve ;)