Core i3 vs. i5

I'm looking to purchase a new laptop and I'm pretty set on getting the Dell Latitude 5420. I'll be using it mainly for Microsoft Office, web browsing, playing music, watching netflix and youtube in 1080p and I was wondering how the core i3 will perform for those tasks. I assume that there will be a benefit in terms of battery life by going with the slower processor but if it can't handle the video then I'll go with the i5. Does anyone have any thoughts on this or if I should definitely go with the i5.