You are looking for a regular expression. This is what Expresso came up with:
Public Dim regex As Regex = New Regex( _
"/vendors/[^/]*/[^/]*/index.aspx", _
RegexOptions.Singleline _
Or RegexOptions.CultureInvariant _
Or RegexOptions.IgnorePatternWhitespace _
Or RegexOptions.Compiled _
)
Public Dim regexReplace As String = _
"<Hello>"
If you are going to use them in the future, get a copy: it's free, and it helps explain, design, and check Regexes. I wish I'd written it!