InfoPath Dev

I've seen a lot of solutions for half my problem, but fall they short of what I need.

I have a Infopath form that is intergrated with a Sharepoint Workflow to approve requests. Once a user fills out the form and submits I need it to save as by month and an number.  For example, the first form filled out in March is saved as 03-001, the second form is 03-002 and so on.  On April 1st, I need the form to save with a file name of 04-001, 04-002 and so on.

First off, is this even possible?  I can get the form to save as the month easily enough and that part is working fine. And I've seen ways I've seen to auto number incrementally but haven't gotten one to work well for me. I just need them to work together.  Is that even possible?

Second, what tools should I use? Sharepoint lists? XML? SQL?  I don't even know the direction I should be heading.

Thanks in advance for any help or direction.  I've looked everywhere for an answer.

So should I take the lack of response as a "that's not possible" response?

The biggest issue with incrementing form numbers is that you always have the chance of two users submitting at very close to the same time. You need to generate your number immediately prior to submit, and even that is no guarantee for a heavily used form.

Does the user need to know the form name? Have you thought about renaming the form as part of your workflow logic? I'm wondering if you may be able to have a better chance of ensuring you don't end up with duplicates that way. Do you submit these forms to SharePoint?

It won't be a very heavily used form, so the chance of duplicate numbers is fairly slim, but yes, I understand it still could happen. 

No, the user does not need to know the form name, just the people processing the form after it has been submitted to the Sharepoint Workflow.  I have explored using Sharepoint to assign the numbers as part of the workflow, but am just about as lost there.  The last promising thing I saw that I haven't been able to explore yet is an event handler.  Do you agree that is a good path for me to explore? 

At this point I'm really lost and am just trying to find the right path to be heading down.

Thanks so much for the response, Hilary.

This blog post of mine has some suggestions for leveraging SQL, but use a bit of code.

I keep wondering if you couldn't add a secondary data connection to the SharePoint list you save the XML to, then use Rules to submit, and have the first rule query that list to get all the form names, and then find the max submitted form for a month....