Convert RGB image to CMYK w/o Photoshop (in Windows)?

[macbeergeek]

After searching the online manual for GIMP I found something under the Colors menu > Components > Decompose, but that didn't seem to do what I need, though in the manual it says, "This filter separates the channels (RGB, HSV, CMYK...) of an image into separated images or layers." and, " CMYK Decomposing: This option is similar at the CMY Decomposing with an additional layer for Black. This option might be useful to transfer image into printing softwares with CMYK capabilities."

Close, but no cigar.