So, I got one of em hp stream 7s and I'm not satisfied with the performance, mainly due to the lack of RAM. (i'm at 90% from fresh boot with skype open) I wanted to install Windows 7 on it, but I got stopped, due to the BIOS not supporting CSM, and, the biggest problem, not being able to use 64 bit UEFIs on there, only 32 bit ones, which is not exactly the easiest thing to find. I don't really care to use Linux on there, if I really need to. The CPU on these is an Intel Atom 1.33GHz quad core
I have Lenovo Flex 10 celeron. I used Windows Embedded 8.1 Industry Pro. Their is x86 & x64. I thought of using x86 since it has only 2 GB of RAM but i found even with 2 GB x64 is better so I switched to x64 it looks OK not perfect but acceptable. the reason I suggest embedded since by default it will not install other MS Metro apps like news ..... etc. you can download an evaluation version from MS directly or you can find an MSDN release by searching this forum. Windows Embedded can be activated by KMS which makes MTK 2.5.3 a perfect solution
You can install any 32bit (Windows 8+) on it using GPT/UEFI setting in Rufus to create the install USB media I do the same on my tablet