Chonni.Silué, you can always defer enrollment for one year. Explain the situation to your college - maybe they'll allow you to start college. It's not easy to get the green card even if you come from a country whose annual quota is generally not filled. For instance, even after graduation, you'll have to wait at least 3-4 years before getting the green card. On the other hand, a green card will open a number of options for you at the university level. Plus it will probably be easier for you to finance your education due to the lack of work restrictions and availability of Federal Pell grants, etc.
On the other hand, if you don't get the green card, you might not be able to enter the US at all through a student visa since your application for the green card will count as an intent to immigrate.
Don't take the green card if you are sure that this diversity lottery application won't interfere with your student visa. You might have to wait a little longer, but at least you'll know you won't be barred from studying in the US.
Though how the hell will you get a student visa now that you have applied for the green card. Won't the application for the diversity lottery itself count as an intent to immigrate?