|Have you tried to get into SAFE mode? Do you have an external monitor that can be connected to test the display? Does the laptop sound like it is still booting with the display off?|
Various problems come to mind with the symptom you are describing.
1. Failure of the hard drive - if the drive electronics fail the BIOS can not see it as a boot device correctly, the result is an extensive delay while the system tries to find a boot device.
Go to the BIOS and see if the hard drive is detected.
2. Corrupt video driver - at the point the BIOS turns video control over to the OS a failed driver will cause the screen failure as one symptom.
During boot once the logo is displayed press the F8 key to get the XP startup menu, select VGA mode to see if the system will boot. If it boots then remove the video driver software and reinstall it.