the easiest thing would be to add something like this near the top of search.asp:
strSearch = ""
if Request.Form("Search") <> "" then
strSearch = Request.Form("Search")
elseif Request.QueryString("searchterms") <> "" then
strSearch = Request.QueryString("searchterms")
end if
then change all existing instances of:Request.Form("Search")
to:strSearch
I haven't tested this, but it should work.