How do you define insufficient consideration?

I have been employed as a sales consultant from 4/99 - 8/04. I was dismissed without cause/reason (as stated in my employee handbook as an "at-will" employee). My company is headquartered in Wisconsin but my sales efforts and home office were in Cook County. Prior to my position with this firm I represented many of the same clients at another company. I was able to transition many of these clients to the current firm because of my solid relationship with them.

I was forced to sign a non-compete in March of 2002. I say forced because I did not want to lose my position of which I was very successful.

Now that I have been fired I would like to start up my own company offering some of the services that my old firm offered. I have received a demand letter from their attorneys stating that I must cease and desist immediately. Whilw I have discussed this with an attorney, I am interested in your opinion. One discussion is insufficient consideration. Each employee was give 3 days of vacation for calendar year 2002. This amounted to only $275.00 to me as like most sales people, I was mostly commissioned based. Might this be considered insufficient consideration?