Since you insist on getting the inferior in-place Upgrade as your introduction to Windows 7, you hopefully did your homework by running the Windows 7 Upgrade Advisor
to be clued to incompatibilities, and uninstalled anything which might conflict?
You can access the install logs to see what the failures were by finding these files:
You can also enter Device Manager during install to see what driver might be hanging boot, likely display, then uninstall it so install completes so you can update it from desktop: Device Manager - Access During Windows 7 Installation.
Also before starting upgrade establish a clean boot by unchecking everything in msconfig>Startup, and msconfig>Services after Hiding All MS Services. Reboot and check back that nothing has returned or turn off in Program Preferences or uninstall it.