Asus is expected to start shipping the Windows XP running Asus Eee PC 4G-X in the United States on April 9th says Laptop Mag.

The Windows XP Asus Eee PC is already on the market in Korea and Japan.
Asus actually predicts that 66% of Asus Eee PCs will actually run Windows XP. I do not see why that should happen. If you have been waiting for the Windows Eee because you are a Microsoft only user, you should give the Linux version a try - it is surprising how well Linux works on it.
I am a Windows user and I do not see the point in running XP on my Asus Eee PC 8G. I just want the new Eee PC 900 with the larger screen and higher resolution.

Laptop Magazine and Hothardware already got their hands on the U.S. bound Asus Eee PC 4G-X and published some unboxing and early review reports.

Shop for Asus Eee PCs on NewEgg and on Amazon.