Credit problems and need help?

Ok im 19 years old. i have no credit. ive tried many places to get lines of credit and all have been denied. i cant get a co-signer because my parents have very bad credit and most of my friends have either no or bad credit. Im about to go back to school and i really need a computer for school cause the one i have no is 1 very outdated (256 mb of ram) and 2 is constantly crashing and locking up. so what should i do should i go to a rent to own place or is that a bad idea?