Just to keep your brains from being tangled up, this is called the Estimator. The sims are what you find on your own EQ and TU reports. They're more sensitive in a way, in that they are specifically tuned to that CRA's formula, but they only let you play with one variable at a time, and it's a limited list of variables.
You can find the Estimator at the bankrate.com link, or on the FICO site. The link is on my siggy below. I love the Estimator!
I use it as my time machine, to see where I would be if I had just put the freakin' check in the mail.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007