Possible Conditional Formatting

Using Excel 2003
I have 9 columns
A: Last Name
B: First Name
C: Initial Training
D: 6 mo. Training
E: 1 Year Training
F: 2 Year Training
G: 3 Year Training
H: 4 Year Training
I: 5 Year Training

In the intial training column (C) I am going to record a month and year
(Mar-10).
I want the "6 mo. Training" column (D) to turn (for example) red fill and
white font on Sep-10. Then in the "1 Year Training" column (E) to turn (for
example) green fill with white font on Mar-11 and so on. How can this be
done. Do I have to put a formula in the cells and then apply conditional
formatting? The problem is, I can only use up to 3 conditions. Note: Even if
I enter the initial training on the day of 3/31/10, I still want the six
month to be Sep-10 and so on. How can I accomplish this?
ANY help would be greatly appreciated, Karen