No. Just do the math and you'll see that it won't work. Windows, when installed, takes up a lot of room on the hard drive. If you where able to "install" it to a CD (not big enough, maybe a DVD) you would be incapable of removing it as in normal operations Windows doesn't put all of itself into memory. Windows = 5GB of code RAM = 1GB? 2GBs? Whatever. You want most of the RAM to be used for running programs so most of Windows is not loaded into memory at any one time. If you do something in Windows, it makes a call to the hard drive (or CD/DVD) and loads the appropriate code into memory for that task. After the task is done it dumps that code to make room for the next. It is a fairly quick process and most of the time completely transparent to the user. But it is a necessary one. If you are trying to start-up a computer from removable storage and still leave the CD/DVD drive free, your best bet is to install a stripped down version of Windows (better yet one of the Linux distros) to a USB thumb-drive. Linux will fit on a 1GB drive with no problem and you might be able to find a stripped down XP version of Windows that will run off a 4GB drive. Hope this helps.