Windows Live Mail client looks better than Thunderbird. If you want to migrate to Windows Live Mail client from Thunderbird, then do as follows:

1. First, you need to backup the Thunderbird folder under the C:\Documents and Settings\Application Data folder and any local folders if any.

2. Install ImportExportTools add-on and restart Thunderbird.

3. Right-click on the folder which contain the mails you want to export. Say Inbox, Sent Mail etc, and choose Import/Export > Export all messages in the folder to EML Format from the context menu. Choose a location to save the exports, say C:\mails\eml-format\Inbox for inbox and C:\mails\eml-format\Sent Mails for sent mails.

4. Open Windows Live Mail client and from the File menu choose Import > Messages > Live Mail. Choose the directory from the previous step where we saved the mails. So at first we will import mails from Inbox folder, so we'll choose C:\mails\eml-format\Inbox folder. Click Next and choose All folders and complete the import wizard. Similarly for the other folders.

5. If you have successfully imported the emails, then it will be shown under the Storage Folders > Imported Folders section on the left pane. Now you can select all the emails under that folder and drag-and-drop to Inbox or any other folder, and organize them accordingly.