A few years ago I was in a simmilar situation involving a web site's colors.

I convinced my client about using a white background by stating that Microsoft probably spent a lot of money studying this very issue and the background they chose for all their application was white. If a study yielded this result, there must be a reason.

As others said, if she's so picky about it, give her the option to reconfigure everything as she wants - since you have a deadline to meet you should probably tell her that you will work on this as soon as the program is functional. This also means that the app will be in use sooner.

The only reason why I would stick to windows' color scheme is because it's consistent and users know what to expect and where to find everything.

alex