From my experience, it is not possible, or rather it is tedious and not portable.
Now, on you Win7 laptop, you can create an Ad-hoc network and after creating it, windows asks, whether you want to share the internet connection. However, the iPad does not connect to Ad-hoc networks. So this will not work directly.
You would have two alternatives:
-Find a software, which lets you create Infrastructure wireless networks on windows 7. (i know of known which does this)
-Setup a wireless router or Access Point, join the wireless network with your laptop, then share the internet connection, and lastly join the network with your iPad. (you are limited to use this at home)
But I would be glad to find out, if there are better solutions out there.