XP

This is a fascinating project from a technical standpoint. They are implementing missing API calls used by newer applications that are missing from Windows 98 and Windows ME. I know what you are thinking, why? Well, why not! Even though their numbers are dwindling, there are still some users that want to use new applications on the old platforms. I'm not going to question it - I just know they exist.

The list of newly compatible applications is pretty impressive:
Mozilla Firefox 3, Adobe Flash 10, OpenOffice.org 3.0, Java Developer Kit 6, Java Runtime Environment 6, Google Picasa 3, PDF-XChange Viewer, Doom 3, Quake 4, Prey, Need for Speed: Most Wanted and many other programs.

You can read more about it and download the bits from here.