It's a bad idea to install Windows 7 on those kinds of hardware. It will only install 32 bit of windows 7, which you will have some limitations on softwares. 64 bit versions of windows 7 will required 2GB of RAM. For your mom 's netbook's specs, I suggest install Windows XP, if you already have it so, stay with it. With Windows 7 installing on that netbook, even if it works, the computer will lag. I don't think anyone here, likes lag. Windows XP will stay supported for about another year or so, if you have Service Pack 3 of Windows XP installed. So don't worry about not receiving updates. Just stay with Windows XP.
Sounds good to me, appreciate it!