hey, i just transfered (well, starting in the fall) from Rochester Institute of Technology to Cornell. This is after my sophmore year btw and I am majoring in Computer Science.
As for UC schools, depending on which ones (Berkeley especially), dont expect to get in if you're out-of-state and dont have perfect grades. They give high preference to in-staters and the remaining spots go to the creme de la creme of out-of-staters. (I applied to Berkeley and didnt get in btw)
If you need any help/have any questions regarding transfering, feel free to PM me and I'll try to answer as best I can.