Ricardo - Welcome to the Board
You pose a very interesting question - to which I do not know the answer
I have edited your thread title to make your problem clearer.
The only solution I can give is to hitch up a floppy drive to the motherboard on a temporary basis. The request for drive A: would be hard coded into the Windows install CD.
Although I have installed beta copies of the next version of Windows called Vista I don't remember if the same situation applies.
With an increasing number of PC's being supplied without a floppy drive there has to be a workaround - I shall be interested to see what other solutions are posted
Even some laptops have SATA
drives now for which drivers may
be needed for a clean install and I am not at all sure that an external drive floppy would suffice - it would not be seen as drive A: AFAIK