|And it was working OK prior to the reinstall? Is it an internal or USB floppy drive?|
"lost functionality" Does that mean a) XP doesn't see the drive or b) it does but the drive doesn't read disks?
If a) does it show in cmos/bios setup? If not check that it's properly identified there and the floppy controller enabled. If it does show then boot to XP and check device manager. Do any problem show there with the floppy controller or floppy drive? You may need to install motherboard drivers.
If b) are you sure the drive and floppy disks are good?
Ding dong the witch is dead. . . .