It's fine, that you succeeded. So even if you should decide to erase Vista from your computer, you now know, that you are able to get XP successfully installed. That's normal. The reason is, that the older OS (XP) eliminates the Vista bootloader. You can repair the Vista bootloader either by booting of a Vista DVD and choosing the "Repair" option or by installing a tool like EasyBCD (prior installation of MS Framework 2.0 or higher is needed). If you don't want a dual boot option at all, you should do the following:1. Boot off the just created XP CD with integrated textmode driver. 2. When you are asked where to install, choose drive C (where your Vista is installed now). 3. Do a quick NTFS format of drive C when prompted. 4. Let Setup complete the installation. Once XP is up, you can run the Disk Management and format drive E (where your first XP installation is). This way you have got an XP singe boot system. If you want to change the size of the different partitions or reunite the drives E and F, you should use a tool like Acronis Disk Director Suite (the XP Disk Management may no be able to do it). Run the Device Manager and look into the "IDE ATA/ATAPI Controllers" section. If you see a device named "Intel ICH9M-E/M SATA AHCI Controller" (or similar), you can be sure, that the AHCI features are enabled.Regards Fernando EDIT: If I were you, I would not erase Vista. Even if you don't want a dual boot system now, the drive C (where Vista is now) would be a wonderful place to get Windows 7 installed one day..... Recenly baught the dv5-1233se (Vista installed), Installed the windows XP. With the SATA driver from the USB floppy drive.I did something wrong & Installing gain the WIndows XP 64 bit, and suddenly boot menu was not coming. I was not able to install Vista with the recovery CDs. Any time I am trying to boot the system HP invent screen comes nothing happens. HP Replaced the hard drive two times (Saying the problem with the hard drive).......... Now may be they will be replacing the third time, but I like to know what the issue is?