Hey ath50, congrats
I graduated from CMU with a BS in Comp Sci., the computer science department there is truly wonderful. Great advisors, great professors, extremely talented kids around you (I always said when I gave tours, "Everyone here is smarter than me in at least 10 ways and I'm hopefully smarter than them in at least one." ). Plus, no where else do you get greeted in the hallways by robots!
At the same time, I have a few friends that went to cornell instead. Their undergrad curriculum is very similar, and the rigor is about the same too. Neither school is big on grade inflation, so don't expect to graduate with a 3.8+ unless you're both lucky AND smart.
Also, I would recommend NOT entering IS, you won't learn much of the good stuff that is in CS.
Here's how I would choose between the two:
CMU:
1. If you want to do and be exposed to lots of research when you are an undergrad.
2. If you are mostly sure about your major. Transferring between departments is now easier than it was when I had first started.
3. If you like doing your homework to bagpipes.
4. If you really really like hanging around nerds all day. CMU is full of art nerds and tech nerds, and everyone else doesn't get any respect.
5. If you like Robotics, speech recognition or AI.
Cornell:
1. If you want a better social life with a more diverse group of people to know.
2. If you want to have a girlfriend who is normal.
3. If you like intertwining mech e / ee/ and cs.
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Job wise, it won't matter at the end. Choose whichever place you feel most comfortable. Teaching wise, the undergrad curriculums are very similar to one another.
Good luck, and PM me if you want more info!