A key for making a good presentation into a great presentation is the color balances. I spent a number of years cleaning, and editing presentations. It is hard to remember that what looks good on your computer may not project well. The color wheel is key. If your presentation washes out, or is to bright and hurts the eyes; your message will be lost.

I have used the MS Powerpoint site as a reference for color balance.
http://office.microsoft.com/en-us/powerpoint/HA010120721033.aspx

Just remember a darker background is easier on the eyes, and helps to project your message as long as it doesn't clash with any graphs.