request parameter encoding not in corret format when IIS 7.5

Question

I had my server with iis 6 and and url's like this: /anuncios/guantánamo/ actually guantánamo is a request parameter that I use to search into my DB using asp.net

Now I move out to another server with IIS 7.5 and I have the same url /anuncios/guantánamo/ but when I retrive this parameter it comes like ¨guantánamo¨ and offcourse That doesnt work for my search. I thinks is something related with IIS 7 Request filtering, any idea? Thanks