R – Getting all the webpages of a SPWeb and subwebs that have a field with a value in Sharepoint

I have a website in Sharepoint 2007. I want to make a query where the field "home" of the webpages is equal to 1 in one specific SPWeb and (this is the important part) its sub-SPwebs.
I can make this work with the site in question and not with the subsites. That is to say: It is not recursive but I indicate it in the "webs scope='recursive'" clause.

I include also the List I want to use, that is to say, the pages (not documents, master pages or whatever) this is whay i look for the "850" basetemplate (the one for pages).

The code I am using is this (i have tried with other methods with the same query and the result is the same):

  string campo="home";
  SPSiteDataQuery qry = new SPSiteDataQuery();

                  qry.Query = "<Where><Eq><FieldRef Name='";
                  qry.Query += campo + "'/><Value

Type='Boolean'>1</Value></Eq>";

                  qry.Query += "</Where><OrderBy><FieldRef

Name='Modified' Ascending='false'> />";

                  qry.Webs = "<Webs Scope='Recursive'/>";

                  qry.ViewFields = "<FieldRef Name='Title'/><FieldRef

Name='Modified'/>";

 //this gives me system privileges
                  using (SPSite site = new SPSite(CurrentSite.ID,

GetSystemToken(CurrentSite)))
{

                      using (SPWeb web = site.OpenWeb("/News/"))
                      {

                          StringBuilder sb = new StringBuilder();

                          sb.Append("<Lists>");

                          foreach (SPList list in web.Lists)
                          {

                              if (list.BaseTemplate.ToString() ==

"850")
{

                                  sb.Append("<List ID=\"" +

list.ID.ToString() + "\"/>");

                              }

                          }

                          sb.Append("</Lists>");
                          qry.Lists = sb.ToString();

                          dt = web.GetSiteData(qry);

                      ..................

So, the only solution I found was to make a loop after the precedent code through the Webs but i don't think this is a very optimized way:

     foreach (SPWeb w2 in web.Webs)
                              {
                                 sb = new StringBuilder();
                                      sb.Append("<Lists>");
                                      foreach (SPList list in w2.Lists)


                           {
                                              if (list.BaseTemplate.ToString() 
== "850")
                                              {

      sb.Append("<List ID=\""
     + list.ID.ToString() + "\"/>");
                                              }
                                          }


                                      sb.Append("</Lists>");
                                              qry.Lists = sb.ToString();

                                          DataTable dttmp = w2.GetSiteData(qry);
                                          if (dttmp != null
 && dttmp.Rows.Count > 0)
                                          {
                                              dt.Merge(dttmp);
                                          }

                                  w2.Dispose();
                              }