Carnegie Mellon is a very good school.
If you want to get a rough (but certainly not definitive) list of well-known, prestigious schools with highly ranked CS graduate departments, find the common entries among the top 20 in the following two lists:
http://grad-schools.usnews.rankingsandreviews.com/best-graduate-schools/top-computer-science-schools/rankingshttp://colleges.usnews.rankingsandreviews.com/best-colleges/national-universities-rankingsI spotted the following common members:
Harvard
Princeton
CalTech
MIT
Stanford
UPenn
Columbia
Cornell
Brown
Rice
Among those schools, Princeton doesn't accept transfers at all and Stanford has about a 2% transfer acceptance rate so you would need to be incredible academically to transfer there. Cornell and Rice have the highest acceptance rates, and those rates vary from 10-20% depending on the year and, with Cornell, which College you apply to specifically.
There's a lot of variety there. CalTech has extreme focus on technology, mathematics, physics, and to a lesser extent computer science. Expect to get a great but one-dimensional education. CalTech will even give you a mathematics and physics exam as part of the transfer application process--and it's not easy at all. Columbia is the opposite with a rigorous and mandatory liberal arts education. Brown gives you a lot of freedom in choosing your classes. Rice is half-way between CalTech and Columbia--the focus is on science, mathematics, etc., but there's a flexible set of distribution requirements that will have you study some topics outside your major areas. Stanford is similar to Rice in that regard. I don't know much about UPenn or Cornell. And finally I've been told Harvard isn't the best school to go to for CS as an undergraduate, although it is extremely good for mathematics if that's your thing.
To get accepted at any of those besides Princeton you will need a better reason for transferring than just prestige, which is all you've talked about so far. I transferred to one of those schools myself, so I'm fairly knowledgeable about the transfer process.
When you write your transfer essays, you'll need compelling reasons for wanting to transfer. You need to explain to the admissions committee why their school is the only one for you while simultaneously not disparaging your current school, and you'd be best to not even
mention prestige. They generally won't admit "prestige hunters."
Don't take this list too seriously. It's a good list, but it's not exhaustive at all. For instance, Carnegie Mellon, a fantastic school for computer science, didn't make the cut because, I suppose, it doesn't have enough "general prestige" (which is more or less what the second US News list deals with, even if they claim otherwise).