How do I use RoutrOS as an Internet Access Manager for wifi?

I set up an open wireless network in a cafeteria where wireless clients can browse the web any time, but now I need to display a disclaimer (agree before you browse) telling the users that they use the free service at their own risk. I have a Dell mini desktop P4, 256MB ram, 2 NICs and 20GB hdd that I could use with RouterOS.

The wireless AP as it is now has an ADSL line with a Netopia Cayman 3347W connected to a D-Link DI-620 (wireless router). Now people can just sit down at the cafeteria and go online. How can I use RouterOS to display a small javascript (which I already wrote) agreement page before I let people navigate the web? I do not need any authentication or strong security, as there are not any computers on this network.

Any help will be greatly appreciated.

Use HotSpot feature for this. see the manual on how to put license agreement instead of login page

Thank you lastguru. I will check the info as you recommend.

There was a discussion, how to avoid login and password typing:
http://forum.mikrotik.com//viewtopic.php?t=3512