The only reason you get the error, "Windows root\system32\hal.dll missing" is because the boot settings havent found the OS and therfore can't load it. Use you're OS cd, enter the recovery console by pressing 'r' and use the 'bootcfg /rebuild' command, just as Barry said. Three cheers for Barry for actually knowing the exact answer in '02.
From: Barry on 11/15/2002CAUSEThis behavior can occur if any or some of the following conditions are true:The Default value in the [Boot Loader] section of the Boot.ini file is missing or invalid.Windows XP is not installed in the location specified in the Boot.ini file.The Ntoskrnl.exe file is missing or damaged.The partition path in the Boot.ini file is not set correctly.General hardware failure.RESOLUTIONTo resolve this issue, use either of the following methods.Method 1Edit the Boot.ini file to restore or correct the Default entry and to ensure that the other entries in the [Operating Systems] section of the Boot.ini file point to the appropriate directories.For additional information about how to edit the Boot.ini file, click the article number below to view the article in the Microsoft Knowledge Base:289022 HOW TO: Edit the Boot.ini File in Windows XPMethod 2Use the Bootcfg utility in the Recovery Console to correct the Boot.ini file:Use the Windows XP CD-ROM to start your computer.When you receive the message to press R to repair Windows by using the Recovery Console, press the R key.Select the Windows installation that you want, and then type the administrator password when prompted.Type bootcfg /rebuild, and then press ENTER.When the Windows installation is located, the following instructions are displayed:Add installation to boot list? (Yes/No/All)[Type Y in response to this message.]Enter Load Identifier:[This is the name of the operating system. Type Windows XP Professional or Windows XP Home Edition.]Enter OS Load options:[Leave this field blank, and then press ENTER].After you perform the preceding steps, restart the computer, and then select the first item on the boot menu. This should allow Windows XP to start normally.After Windows XP has successfully loaded, the Boot.ini can be modified to remove the incorrect entry.For additional information about how to edit the Boot.ini file, click the article number below to view the article in the Microsoft Knowledge Base:289022 HOW TO: Edit the Boot.ini File in Windows XPMethod 3Start the computer by using your Windows XP CD-ROM. Press any key to boot from the CD.After the setup files are finished loading press R to repair using Recovery Console.When you are in the recovery console, select the installation to log on to (usually number 1), and then press ENTER.Login to the Administrator account by typing the password for this account, and then press ENTER.At the recovery console command prompt, type the following command, and then press ENTER:For Uni-Processor systems:expand cd-rom:\i386\ntoskrnl.ex_ drive:\Windows\system32For Multi-Processor systems:expand cd-rom:\i386\ntkrnlmp.ex_ drive:\Windows\system32\ntoskrnl.exeCd-rom is the drive letter of your CD-ROM drive, and drive is the drive letter of the hard disk on which windows is installed.If you receive a prompt to overwrite the file