For the upgrade did you ensure all AntiVirus, Firewall and stuff like that was disabled, perhaps it may be a good idea to upgrade in safe mode, although I've never tried that myself, and can't confirm it would work.
As for the new install, have you installed any third party scsi drivers in Windows setup as applicable. May need to install at the start of the Windows installation.
Try using the XP Home disk on the new drive as a process of elimination. Have you done the Master / Slave thing on XP, I can't remember if its required, someone help me out there.
I tried several things with the same result.
I finally took the fresh hard drive out and put it into another machine and using the same cd and the same hard drive the install went as it should.
So the problem is with the hardware in that machine.
SO what could the problem be...
I checked the bios for boot sector protection and found none.
There are no other hard drives in the system.
No floppy drive
One CD burner one dvd burner
The dvd burner was new so I even tried the install without it in the system.
I tried the install from both drives.
I replaced the ram with some known good ram chips.
Video is onboard... Actually everythng is onboard...
I tried it with and without the maxtor hard drive setup disk...
can you try to format the clean drive into FAT32 file system? Then install windows98SE(remember to create a bootup disk first) and do a WinXP Pro clean install on it? It usually works for me no matter it's on a PC or laptop. I prefer installing windows98SE first because it is always faster to install/upgrade Windows XP in windows mode compared to running the cdrom:i386\Winnt.exe setup from DOS.
The DVD recorder was one that had slots for memory sticks.
Even though I disconnected the ribbon cable in trying to figure out the problem I did not disconnect the USB wiring for those memory card slots...
I also found a link on the Microsoft Site where Roxio products can cause the same problems...