I have tried the rent-a-center once, and it was a good experience. Tho I think I payed wayy to much for the pos laptop that I got. I believe it was like 30-40 bux a week or something, and for that much a week (4 times as much a month) you could get a sick laptop.
If ur really looking for financing help, try the dell outlet as theyr pretty lenient and have some good deals. Also go to ur local bank and apply for a personal loan. As long as u can show that u have a steady income (which u seem to have as u can afford to rent a laptop) you should have no prob getting a loan.
I myself went thru dell financing and got a 2k credit line as an 18 year old with a minimum wage part time job.