Need Help with Web Service Output

Hi, I'm new to this forum. I'm hoping someone could point me in the right direction to start troubleshooting my problem. I've created my first Web Services project. My output is an xml which is correct, but the data that's being returned is also in xml. My output looks something like this below. My xml data is being passed as a string instead of xml:
<?xml version="1.0" encoding="UTF-8"?>
<string hmln="http://vimeo.com"><?xml version="1.0" encoding="UTF-8"?>
<rsp generated_in="0.6478" stat="ok"><videos><video><tags><tag>.......
</tag><tag>........</tag></tags></video></videos>< /rsp></string>

Is there anything I can do in get my xml data to format properly. Below is the WebMethod used to retrieve the data from my .cs files. I think I will need to make the changes here. Any advice would be appreciated.

[WebMethod(CacheDuration=60)]
public string GetVimeoXMLPage(int PageNumber)
{
int pnum = PageNumber;
VimeoXML page = new VimeoXML();
string xmlResult;
xmlResult = page.getVimeoXML(pnum);
return xmlResult;

}

Thanks