The 1001HA is reportedly available with Linux or Windows pre-installed, although the Windows version seems most widely available.
Debian GNU/Linux Squeeze installation :
Wired networking is supported in the 2.6.32-5 kernel and allows net installation.
Wireless uses RALINK 3090 chipset. To get wireless working, download and install the RT3090-DKMS package :
You can also download and compile the latest driver from the manufacturer's site :
http://www.ralinktech.com/support.php?s=2
A full Debian GNU/Linux Squeeze installation procedure for the ASUS EEE PC 1001 HA is available here (french language) :
Booting with modern kernels requires the kernel command line parameter acpi_osi="!Windows 2009" or acpi_osi="Linux" otherwise the eeepc-laptop module is not loaded.