vbs文件搜索及过虑有关问题

vbs文件搜索及过虑问题
如我有一个文件1.txt内容如下:
xxxxxxxx1xxxxxxxx
a1
b1
c1
xxxxxxxx2xxxxxxxxxx
a2
b2
c3
xxxxxxxx3xxxxxxxx
a3
b3
c3

我想写一个vbs脚本读取1.txt,搜索x2关键字,并同时把从x2当作开始行的4行内容输出到2.txt。我不知道怎么做?大家有什么好的方法吗?
如果脚本运行正确,应当2.txt是显示:
xxxxxxxx2xxxxxxxxxx
a2
b2
c3

------解决方案--------------------
VBScript code
    sFile = "a.txt"
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oFile = oFSO.OpenTextFile(sFile)
    iCount = 0
'Do Until oFile.AtEndOfLine
'    str = oFile.ReadLine
'    Select Case iCount
'        Case 0
'            If InStr(str,"2x") Then
'                iCount = 1
'                WScript.Echo str
'            End If
'        Case 1,2,3
'            WScript.Echo str
'            iCount = iCount + 1
'        Case Else
'    End Select
'Loop
    For i = 0 To 3
        str = oFile.ReadLine
        If InStr(str,"2x") Then
            WScript.Echo str
        ElseIf i > 0 Then
            WScript.Echo str
        Else
            i = i - 1
        End If
        If oFile.AtEndOfLine Then Exit For
    Next
    oFile.Close
    Set oFile = Nothing
    Set oFSO = Nothing

------解决方案--------------------
第四行插入:
Set oFileWrite = oFSO.OpenTextFile("b.txt",2,True)
然后下面的 WScript.Echo 替换成 OFileWrite.WriteLine
最后加上: 
oFileWrite.Close
Set OfileWrite = Nothing