Does anyone know where I can download the Windows XP USB 2.0 generic drivers from?
USB 2.0 drivers are part of SP1 &SP2 updates. and SP4 in Win 2000. you can also download them directly from microsoft download center.
Being more specific, I need a generic driver for a USB 2.0 (FS) Flash Disk. Are those available on Microsoft's site too?
Your best chance of finding what you need would be at USBMAN. He has a great many USB drivers archived.