I'm in a very similar position myself. I'm about to enter my 3rd year at UT Austin, with a double major in Business (MIS) and Computer Science. I have gotten offers to co-found 1 or 2 startup ideas with adult founders that have had very successful companies in the past (that they started!). I was originally only MIS, but my interest has always been in tech tinkering so CS was a must.

I've talked to tons of people and asked this same question and I've learned that a CS degree is VERY useful. Besides engineering, it's one of the most valuable degrees you can get. Many companies don't care about you grades if you're in CS / Engineering, they care about your experience, intelligence, etc. I would strongly recommend working on a startup idea on the side and/or getting an internship in the semester (if no startup) or a full-time internship next summer. Grades are important, but honestly if you have around a 3.0 - 3.2 and you're doing a technical field and you got good startup / internship experience, you're much better than a 4.0 CS guy with very little experience, hands down.