Its very safe, but unfortunatly only for linux.
Well, the thing is, he doesn't have the install CD for Windows, and he is the type who is used to many Windows things (MSN, Limewire). So he won't do it if there's a risk of losig Windows. Or not yet. Even though he knows about Jabber and that LW works under Linux as well.
And I have another friend, who would like to try dual boot, and he has the same problem. He's a gamer, and has a huge HDD, with some windows or another. So, does partition magic or QtParted damage the data on the existing partition?