help in upgrade to xp pro please?

I really need help in my problem please?
i have a laptop , the os was xp home edition, i tried to upgrade it with xp pro, but i couldn't make it, and i installed partition magic on it to format it, now the format hasn't finished and the system gives me an error Loading operating system..
how can i manage to install again the xp pro please inspite of my laptop does not have a floppy dist unit?
Regards
Karwan