Is there a way of learning from the IRS how much I have already sent them for 2007? I would prefer online?

I am about to file my return for 2007, after filing an extension earlier in the year. I mailed a check in estimated tax, but I am having trouble locating it or my records of it. I have two bank accounts and so far neither shows a record, though its possible I mailed it at a different time than I thought. As you can see I'm not organized, but its been a chaotic year. My question is can I learn what I have already sent to the IRS, without going through too much trouble? For example I would love to be able to do this online, as I hesitate to speak to them on the phone as I don't want to encourage any more investigation into my return than is necessary. I will see my accountant in a few days and then mail the return, but I wish I knew what amount I had already paid. Any feedback appreciated.