Windows 7 is now working with Windower, Aikar just posted a new beta version of Windower that is compatible with Windows 7. The official Windower forums thread can be found here, or you can go to the thread Aikar posted here.
Info for 64 bit users:
If you crash going from POL to FFXI launch, try loading Internet Explorer 8 32 bit in the background (doesn't even need to have a webpage loaded with it). It somehow allows FFXI to launch with Windower for most people.