Today I installed Ubuntu 9.10 64bit for the new Asus K40ID notebook. It was relatively a smooth process with only one problem related to X.
Firstly I shrunk the Windows 7 data partition (Asus keeps OS in C and others in D, with another hidden Fat32 recovery partition) with Windows 7's built-in disk manager. It was a nice add-on since Vista. Then I boot the install CD (cum Live CD), check everything is fine (including X and wireless). Then I partitioned the empty disk (swap, Linux1 and Linux2). Linux 2 is empty now since Ubuntu 10.04 LTS is on the way. Then I installed Ubuntu 9.10 x64 to the Linux1 partition. Everything is fine. However, after reboot, the screen just flickered and could not go into X. So I had to boot into recovery mode, used the wire connection, installed the Nvidia proprietary driver.
After that, I have no issues any more. X is fine. Wireless is fine. The Fn key also seems to function well. Sound is fine.