Take a look at ETF, assuming that you are concerned with room/speaker acoustics. Helpful website and excellent product.
I agree with Kal. We, and all of our authorized dealers use ETF. We manufacture 2 test kits, a professional one for our dealers, and a standard one for enthusiasts. It has the microphone, pre-amp, cables, software and carry case. This might be the type of thing you are looking for, it can be found on our software page.
You have to have line in. Mic in will not work. If you only have mic in you will need an external sound card. There are a few USB based ones that are good. We sell a very high end one by ESI for our professional kit ($300), but there are ones that are just as good as your internal one, perhaps better for $40 by Creative.
We sell and recommend an electret condensor microphone we import from Germany. It's $250, very flat and accuarate for these types of measurements.
What you will need to do with the EAD ovation is plug into one of the stereo analog inputs. Set the Ovation to stereo--no processing. Then on the output of that same channel, switch the connection to each amplifier/speaker combination manually. This will allow you to measure and calibrate each speaker independently. The one exception is the LFE. You should do this in the same manner. However, if you have multiple subs, they should all be connected and on and calibrated together. This may sound complicated, but it really isn't. If you need more assistance it might be easiest to call us.