Conditional Formatting using dates

Hello, I have a training spreadsheet which I enter the date someone has undergone training. I want a red, amber, green system to alert me when training is next due. Each training is segregated into quarters. If someone attends training on 01/01/10 and this is entered in a cell I would like this cell to be coloured green.

Their next training would be due in the first quarter of 2011, therefore by 31/03/11. Once 01/01/11 was reached their cell containing 01/01/10 should turn amber, once 01/04/11 was reached their cell containing 01/01/10 should turn red.