In MS-DOS or similar, you probably will need to add the /U parameter to skip the checking of current format:
format b: /u /f:360
However you should be aware that a 1571 drive can not (*) read PC floppy disks, and the same is true in the other direction. In order to transfer data to and from a Commodore floppy disk, there are several alternative methods of which the X-series cables are the most common and easiest to get. If you run MS-DOS on your Pentium computer, you could get an XE1541 cable. If you run some Windows NT derivate (**) or Linux, you will want an XM1541 cable which is almost the same except two wires are swapped.
As a side note, back in the old days I found that floppy disks once used on a PC were almost impossible to reformat and use on e.g. a C64. Your milage may vary, but still to this day I try to keep apart disks used with a MFM encoding floppy drive and disks used with a GCR encoding drive. It may not make sense but we all have our little ticks and tricks - this is one of mine. :-D
(*) Ok, you can make an internal hardware modification and use Big Blue Reader, at least on a C128 but that might be a little out of scope here.
(**) I once ran Windows 2000 on a Pentium 166 with 64 MB RAM. It was not too bad, as long as you stayed away from starting Microsoft Office.
I am not aware of this cable Raven mentions, but if you are interested about the X-series cables, you can visit this site:
This page is maintained by Kovács Balázs, i.e. one of your Hungarian landsmen which would simplify a bit if you feel the need to contact him personally about something, e.g. ask if he still has any cables for sale.
Hm, ok. I thought the XA cable only was useful with the handful of motherboards that has a non-standard parallel port which doesn't handle XE/XM cables. Then again, the only application I'm aware of that doesn't handle the XM cable would be the free version of 64HDD. I think for example Star Commander handles any cable.
The question is though if this is what DataSette is trying to do, transfer Commodore software from his PC.