[Eastern Girl]

Quick question for the chefs on CP, how important is it to get the exact ingredients specified in a recipe?

I have been nominated to make a birthday dinner and birthday cake for my friend, and I can't cook or bake to save my life. I am pretty sure I was nominated so that my friends can take turns mocking me and my cooking, once I fail miserably.

Anyways, I have chosen my recipes, and done the shopping but was unable to find some of the specific ingredients. For instance, instead of regular brown sugar, I have Golden Yellow Brown Sugar (which I still don't get, how can it be yellow and brown?), instead of unsweetened bakers chocolate, I have semi sweetened bakers chocolate and instead of butter, I have margerine.

So, I am pretty stupid when it comes to this stuff, so my question to everyone, are these differences things that will really change the taste of the food?

Any help is appreciated.