1. Did the trouble begin with the "first" reboot after installing the new hard drive?
2.
Disable restarts. To stop continuous restarts, you should select "Disable automatic restart on system failure" from the Windows Advanced Options menu. Generally it should stop on a Blue Screen of Death (BSOD).
3.
Backup Data. If you don't care about the data, that makes it easier. Simplest thing then would be to run a "
chkdsk /p /r" on file system of your system drive from Recovery Console. If that doesn't work, either attempt a
repair installation or a
new installation of the operating system.
If you care about the data, you should back it up before proceeding. Normally this would be done by
slaving the hard drive to a known working computer system. If your working computer is a laptop, I'd assume you'd need to use a USB interface to access the slaved drive. You'd either need an external drive enclosure with the correct internal interface (IDE PATA or SATA) or a cable with the correct adaptor to convert your drive interface to USB.
Or you could boot the desktop to a
Live CD, and attempt to save your data off to CDs/DVDs or USB drives (thumb, flash, hard drive). A Live CD contains a bootable program or operating system that loads from the CD instead of the hard drive. Although this is very doable, I really can't walk you through it.
Or you could place
another hard drive in desktop as your master drive and install a new operating system to it. Then if the desktop appears functional, slave the original hard drive to it, to save the data and/or repair the original operating system.
A risker approach would be to install new operating system to a
different partition of the original hard drive (if your Windows XP CD permits this). You could also attempt new installation to different "Windows" directory on same partition as original installation, but it's messy and I don't recommend it. It's worth repeating. If you need to save the data, use a working computer to recover it.
4.
Which computer? What is the Make and Model Name/Number of the Acer eMachine? Try to get it from the sticker or plate on back of the machine along with the Product Number. I'm assuming your system came preinstalled with the operating system. I'd like to see what recovery media (recovery partition/CDs) and instructions eMachine provides.
5.
Restore Points. Did you make or have any recent system restore points?
6.
To boot from CD, you either need to tell the eMachine explicitly to boot from CD/DVD drive or go into CMOS setup to ensure CD/DVD drive comes before the hard drive in the BIOS boot order. The documentation for your computer should explain how to do this (and should be available for download on the manufacturer website support pages).
7.
Recovery Console. If your Windows XP CD
supports Recovery Console, it should appear as an option on the "Welcome to Setup" screen. Screen should appear as follows:
Windows XP Home Edition Setup
Welcome to Setup.
This portion of the Setup program prepares Microsoft(R)
Windows(R) XP to run on your computer.
o To setup Windows XP now, press ENTER.
o To repair a Windows XP installation using
Recovery Console, press R.
o To quit Setup without installing Windows XP, press F3.
If it
doesn't support Recovery Console, there's an
iso image you may download and "write" (not "copy") to a CD-R.
Download link is:
http://www.thecomputerparamedic.com/files/rc.iso.