Syllable is an open-source hobby OS for x86 and compatible processors. The OS is tiny, compared with the gaint Linux distributions like Fedora and Mandrake. And now Michael Saunders has recently bundled QEMU CPU Emulator with Syllable, so that one can run Syllable on Windows! No need to burn CD, partition your HDD and install any boot loader! Just download, unpack and run!
It is so easy! The only drawback is that QEMU runs 10 times slower than a real PC, so your Syllable will be painfully slow. If you really like this distro, you should install the real one which is lightning-fast!
P.S. Alternatively you can try the Syllable LiveCD. Just burn the CD and put it into your CD drive when booting your machine. The OS will be loaded from the CD directly. If it doesn't, check your boot sequence (e.g. CD drive > Floppy drive > Hard drive), and check to see if your BIOS supports CD boot. Of course, since it is loaded from CD, you will lost your work after system shutdown and your CD drive will read like crazy when loading programs.