121264 Web Tool

I want a simple programme that achieves two things. 1. To be a website tool that other people will copy and paste to their website to give me backlinks, a bit like a webmaster tool for link popularity 2. It is for automotive websites. It needs to be a small box with three inputs. What the programme/ link should do is work out a monthly figure from deposit (in �) e.g �500 period (in no of months from 12 up to 60) e.g 48 months Ballon left to pay at end. e.g �3000 balloon at end There also needs to be a way of altering the interest rate. A simple project. I ticked th Java box, but I do not know the best format in honesty for the job. Use your skills and experience to decide for me. Regards Ian