How can I get my iPad 2 to view a website on a laptop over an adhoc network?
This isn't an Apple specific question, but the simplest way to do this is to use the IP address of the laptop. There are various ways of determining the IP address of the laptop. You may be able to find it by hovering your mouse over the wifi icon in the taskbar, or if not open a command window and run 'ipconfig'.

Once you have the ip address, you can browse to it from the iPad at the URL:

http://a.b.c.d/

where a.b.c.d is the IP address of the laptop.

You will have to ensure your Windows firewall is allowing access and ensure IIS is listening to this IP address - by default it listens to all IP addresses on the machine, so unless you changed it, you  should be ok.