The ASUS 1215 came out of the box with Windows 7 premium home edition. The nice thing that ASUS does is partition the drive into two drives. There’s a 100G C:\ drive and the rest of the drive is in a separate D:\ drive.
This makes loading Linux extremely easy. The D:\ drive can be removed without disturbing the Windows installation. The one gotcha is that ASUS uses 3 primary partitions on the drive. One for the C:\, one for Windows covert, and a third for system restore. This means you will want to install Linux into an extended partition. Most distributions want at least one partition for Linux and a swap space.
I added three partitions to my 1215: a 4G swap, a 128G ext4 mounted at /, and the rest in an ntfs partition mounted as D:\ in Windows or /stuff in Linux.
My thought is to place music, movies, and pictures in /stuff so they will be accessible in both Windows and Linux.
I’m also using smaller partition sizes to see if I could live on a SSD machine with limited resources.