Windows Live Messenger 2009出來啦，但是依舊默認不能同時開多個帳號，MSNShell依舊不支持新版本的MSN，我們只能手動修改注冊表來多開MSN了！
方法很簡單，因為Vista和WinXP的注冊表基本類似，icech這里導出了一個WinXP下Windows Live Messenger 2009多開的注冊表信息，你只需要導入進去就OK了！
經過測試在WinXP和Vista下均有效：
1、文件方式導入到注冊表
打開文本編輯器，比如記事本。將以下藍色文字拷貝進去，另存為MultiLive.reg，保存。然后雙擊此文件，將注冊表信息合并。
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Live\Messenger]
"MultipleInstances"=dword:00000001
2、手動修改注冊表
其實原理同上，只是手動修改一下。
開始->運行->輸入regedit->找到
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Live\Messenger
增加一個新建DWORD值，名為MultipleInstances，數值數據為1。（如圖所示）
修改后關閉注冊表編輯窗口就可以了。這樣就可以同時打開多個MSN登錄不同的帳號了！如果你想卸載Windows Live Messenger 2009的話可以參考鏈接文章。
相關下載：Windows Live Messenger 2009正式版下載
原文：How To Enable Polygamy In Windows Live Messenger
Many of you will have several WLIDs, and want to sign into Messenger with more than one of them. Until now you had to seek refuge in a patch or add-on to be able to do so. Not anymore! Microsoft’s John Weisenfeld just shared a little trick with me to enable this, which I’m going to share with you.
The trick involves registry editing, so please follow these steps very carefully:
1. Start regedit (admin)
2. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Live
3. Right click Messenger and create a new DWORD called MultipleInstances
4. Right click the newly added registry key and choose Modify
5. Set the Value data to 1
6. Close regedit
All done! Now you can launch Windows Live Messenger as many times as you want, and sign in with as many WLIDs you want, on one computer. Just don’t try to sign in with the same WLID more than once on one computer or it will throw error 80071392 at you!