Since the source computer utilizes Windows XP you have access to Outlook Express which can help you transfer the email files necessary to your Windows 7 machine. The steps are also outlined in this
Microsoft Answers forums thread, but just clarify; the process would be as follows:
• Since Outlook is already configured with your email accounts, a PST file already exists.
• Start Outlook Express and import the messages from Outlook. Close Outlook Express when completed.
• Next, you will need to copy the Outlook Express store folder from the Windows XP computer to the Windows 7 computer. To find its location on the Windows XP machine, click on Tools>Options>Maintenance>Store Folder
• From the Windows 7 computer, start Windows Live mail, and choose to import messages from the Outlook Express store folder you copied over.
Hope this helps you out!
Windows Outreach Team – IT Pro