From: "Rich Gauszka" 

Silly me - I figured that if the motherboard supported USB floppy drives
that any would work - Found out the hard way I was wrong when I tried to
install an AHCI driver with an unsupported USB floppy. The bad part is I
was able to do the initial F6 install with the USB floppy but the second
time during the install that XP needed to load the drives it couldn't see
the floppy. Luckily I had an older USB floppy in the closet that was
supported


http://support.microsoft.com/default.aspx/kb/916196

This issue occurs if the USB floppy disk drive is not supported for use
during Windows XP installation. To be supported in this situation, the
drive must be listed in the Txtsetup.sif file.

The following USB floppy disk drives are included in the Txtsetup.sif file
and are therefore supported for use during Windows XP installation:

Plug and Play ID  USB floppy disk drive model

USB\VID_03EE&PID_6901  Mitsumi
USB\VID_057B&PID_0000  Y-E Data; Sony part number 09K9835
USB\VID_0644&PID_0000  TEAC; IBM option part number 27L4226, FRU
05K9283

The following USB floppy disk drives are not included in the Txtsetup.sif
file and therefore are not supported during Windows XP installation:

Plug and Play ID  USB floppy disk drive model

USB\VID_03F0 &PID_2001  HP
USB\VID_054C &PID_002C  Sony
USB\VID_057B &PID_0001  Y-E Data
USB\VID_0409 &PID_0040  NEC
USB\VID_0424 &PID_0FDC  SMSC

--- BBBS/NT v4.01 Flag-5