The short answer is "yes", but you need to get the syntax correct and may have to temporarily remove the "read-only" attribute of the file, if set. If the operating system is installed to the first partition (1) on your first or only hard drive (0), the following basic "boot.ini" should work:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows XP Home" /fastdetect
To identify your operating system, you can replace the string "Windows XP Home" with any text you wish; e.g. "Microsoft Windows XP Home Edition". If you do the background reading, you'll see that you can add additional lines to invoke the same operating system with different options. A useful addition would be an invocation line that starts the operating system in "Safe Mode".
If you read very carefully, you'll find you can install the Recovery Console to your hard drive as an additional boot menu option. The advantage being you may be able to boot to Recovery Console without breaking out the Windows XP CD.
As mentioned in an earlier reply, you can also use the "bootcfg /rebuild" command from the Windows XP Recovery Console to generate a "boot.ini" file.
Some background references:
How to rebuild the Windows boot.ini Additional information and help with the boot.ini Display a Custom Boot Menu Every Time You Boot Windows XP