Activated AIM module not showing up

I'm trying to test out a client's authorize.net gateway using the AIM module, and have installed it and entered in all the relevant information. However, when I go through checkout to test it, the checkout_payment module only says "Check or Money Order" is valid. There is no link or form to enter in a CC for authrorize.net. I had the SIM version up and was getting the form, but when I removed that one to use the AIM version, I get nothing.

I searched all over the forums and what not for a similar problem, and I did see a post where someone mentioned something similar, however it was never really answered. Do you need to have SIM running to also use AIM? Any clues as to why this isn't showing up?

EDIT - I just remembered, because I'm sure these questions are coming...but I'm on an IIS server, with CURL installed according to phpinfo(). I also have SSL running correctly.

After following the trail of variables through the code, I found out that the problem seems to be that when I install authorizenet(AIM) and set it to accept payments, it's not updating the MODULE_PAYMENT_INSTALLED record in the configuration table in the database. The keys specific to authorizenet(AIM) all seem to have been added and set correctly, but like I said, the actual configuration key that php checks to determine what modules to allow isn't being changed. Is there some other place in the admin that I'm supposed to be setting what payment method to use? And if so, is there a reason why it is in two places?

For the time being I just added authorizenet_aim to the MODULE_PAYMENT_INSTALLED key manually, but obviously I'd prefer not to make manual changes to the database if possible.

Any insight into why this is the case would be helpful.

Yours is the first I've seen someone report that activating a module failed to set it properly in the list of enabled modules.