CORE I3 330UM WITH ati card versus core i5 with intel hd

I have a question regarding what processor and graphic package I should get for my new laptop. I'm buying a HP touchsmart tm2t for graduate school and try to figure out what I should get as a customized option. For $50 more I can get a core i3-330um with a swithcable ATI Mobility Radeon HD 5450 upgraded OR a core i3-330um with intel hd graphics, or for 75$ more I can get a core i5-430um with intel hd graphics.

I'm not really planning on gaming very much (not sure yet), but I really would like the better battery life I could get due to using the tablet in class for note taking, ms word, powerpoint,etc. I will probably use some stats software (psychology major)also and use it for a library as a ebook/pdf reader. I jsut want people's views on what would be best for me, and if getting a core i3 may hurt me in the long run for future applications that may come around and me really needing to buy a core i5.

Thanks!!!