page redirection help needed

hello there,

i have a wordpress blog. in this blog there is a event page. in event 4 themes are used as sub pages. like

home
event
-halloween2006
-halloween2007
-halloween2008
-halloween2009
contact us

i have managed to make the theme pages. but the problem is that my client is not liking the link structure.he wants to change the link.here is the current link structure
http://localhost/bonzabas/?theme=halloween2008&page_id=246
he wants
http://localhost/bonzabas/Events/Helloween2008/

can it possible??? pls help me…pls pls

thanks in advance