|Does it work OK when a different monitor is connected to the PB?|
If so, the problem may be with the video settings. Boot to safe mode (after starting up the PC, start tapping F8 before the OS starts to load. Choose 'safe mode' from the menu.) Then open display properties and choose to save those settings. Shut down and reboot to normal mode. Then readjust the settings to something the PB monitor can handle.
If a different monitor doesn't work then the problem is elsewhere, possibly the hard drive.
The order of boot devices should be adjustable in cmos/bios setup. You can set the floppy as first boot device there.