While not a direct answer to your specific question, this may still be a solution.
You can add both machines, 7 and XP, to the same workgroup/network space and allow the sharing of a folder on your Windows 7 machine.
Access the share through the XP VM and copy over anything from XP into the Win 7 share.
In the same respect, you could share a folder on your XP VM and access it from Win 7.
If you need help setting that up, I can provide more details.
In addition, if you configure the network locally (within your machine and it's virtual adapters), I don't believe it will even need to communicate with your router maximizing transfer speeds.
Edit:
http://howtotechtutorials.com/how-to-share-folders-in-windows-7-without-homegroup/
http://kb.seattleu.edu/oit/KnowledgebaseArticle10028.aspx
Noted by BroScience below:
You can't copy files in out of the vm window, you have to use the drives inside the vm. If you look at My Computer in the XP VM, it will show you the drives on your host machine. That's where you copy it. You also don't need a synched folder, just use the shared folder as the primary and it will always be accessible in the vm and in your host OS.