Calculators (HTML Javascript) to replace Flash

Have a need to rework some Flash based calculator content into direct on page HTML javascript content in order to enhance accessibility. An example of what has gone before can be seen here ([login to view URL]). Graphically we can provide whatever is required, but would like it to be similar in visual approach and functionality to the flash example. This scales to full window, but would be approx 550 pixels wide on page. There are currently 3 of these to be created, but all work on a similar model, set of input options etc. Basis: Fixed "vehicle price" value from user selected "vehicle" list. Option to "add warranty" at one of 2 prices based on chosen vehicle. User choice of "deposit" within fixed range controlled by "minimum deposit" to "minimum permitted loan value". User choice of "repayment period". Return values "Monthly payment", "Total Amount payable", "Total amount of Credit", "Vehicle", "Interest Rate" and "APR". Then all costs are presented back to user as per example. With Flash this is instant, can it be live updating with javascript or will it require "update" button? Ability to then print out quote with added small print also required. Would want well commented script for ability to make simple amends to selectable lists and rates.