If you’re making a file to be placed in presentation software and word processors, you should be using RGB instead of CMYK. Many of such programs only understand RGB. Also, since this is a logo, PNG format would probably make a better image than JPEG since it will not introduce artifacts at the edges or high contrast areas.
Microsoft programs are notoriously awful. ER... I mean awful at working with CMYK images. In Windows XP if you get the properties of a CMYK image it will tell you it has "CMYK Color Scheme". No, CMYK is a colour model, not a colour scheme. A colour scheme would be Cyan carpets and Magenta throw pillows. Use RGB images with Office programs, and PNG for anything that does not use a lot of shading, like photos or gradients.
Well, what do you think Office products know about CMYK? Zero! You are looking for an error in the wrong place. Converting to RGB is the correct procedure for embedding files in MS Office documents. And not to put too fien a point on it: As long as you can't guarantee that all screens and printers are color managed (which I never have heard of being the case in an average business office), all your concerns regarding constency of color reproduction are pretty much missing the mark, anyway....
Scott and Mylenium,
Thanks - useful comments. It's pretty clear that I'm going to have to switch to RGB for the jpg file and live with the colour difference (fair point, though, about the variability of monitors and printers making the question somewhat academic). Png would be a viable alternative except that one version of the logo involves some drop-shadow shading which ends up looking dreadful on some desktop printers.
(By the way, I have another question about file formats for these logos but I figure it would be better to start another thread rather than continue here, since it's on a slightly different subject - hopefully that will make it clearer for anyone else who's searching for information on the issue.)
Well, what do you think Office products know about CMYK? Zero!