I have two hard disks, with each hard disk having a single Windows XP system partition installed on it and multiple partitions.
Will there be a single boot.ini for all the hard disks and where will it be (first or second hard disk)?
I have two hard disks, with each hard disk having a single Windows XP system partition installed on it and multiple partitions.
Will there be a single boot.ini for all the hard disks and where will it be (first or second hard disk)?
Yes, there is a single boot.ini file, usually located in C:\Windows.
You can check it from System configuration Utility: Start menu -> Run and type msconfig.exe

Short answer: There should be one boot.ini per drive.
Long answer: There should be one boot.ini per drive, along with one bootloader for each drive. The one used is decided by the BIOS's boot order.
Actually, the boot.ini is located in the root of C: (C:\boot.ini). Also it's a system file so you won't be able to see it unless you enable the option to view System/Hidden files in Explorer (or "dir /ah" via cmd-line). The msconfig utility noted above just lets you see the contents of the boot.ini and change them via a gui instead of having to edit it with something like notepad.
This article http://support.microsoft.com/kb/314081 explains many of the options.