I found this after my windows xp got corrupted and I was reluctant to format my either of my hdd's (I have some files I'd rather not lose). You download a small file (approx. 2.7MB), when you run this file it asks you to insert a windows xp cd and a blank disc. It uses files from windows and from the download to burn a cd that functions as an OS from your cd drive. It has a number of different features including a full GUI and network support. It is extremely helpful for transferring files if your windows dies, and a number of other things. It is not illegal. You can download it for free from www.nu2.nu/pebuilder . You never know when you might need it!