Kath,it is very likely that you will use Eviews. While Stata is more used in universities, Eviews is used in businesses because it's lot easier and user friendly than Stata. If you have some experience with Stata then it'll take you very little time to learn how to use Eviews. Really, it is an extremely easy program, especially if u are using Stata.Now, u must be clear about one thing. Valuation (DCF and similar) is one thing, econometric modelling is something completely different. In econometric modelling is all about regressions. I honestly doubt that you will use Excel for regressions, since excel can only perform very simple OLS. Probably, you will use Excel for descriptive statistics and reporting.The best thing you can do is relax and enjoy the free time u have before ur internship. Since you are an undergrad at the end of 1st year, they know that you are NOT an expert in econometrics. They'll teach you everything, but they will not require you to know how to run a simple regression. Econometrics requires a lot of practice; there is a big difference between theory and empirical applications. Relax, you are a 1st year undergrad, it is just normal that you have little econometrics experience. Don't try to get in there as if you were a PhD student because, believe me, econometrics requires time and patience.