Looks like Microsoft will never be able to have a smooth launch. After Windows 7 was launched, there were several forums which were filled with issues related to upgrading to Windows 7.

Several websites have covered issues ranging from continuous reboots to upgrades getting stuck at 62%.

If you are someone whose upgrade from Windows Vista is stuck at 62%, it is time to head to this Microsoft KB article for a fix. Here is the resolution, thanks to Microsoft and Lee Matthews from DSQ.

Important Do not use this resolution if the upgrade stops responding at a percentage other than 62% or if the log entries are not logged. For more information about how to open the Seupact.log file, see the More Information section.
To resolve this problem, follow these steps:

1. Restart the computer. Then, your computer will roll back to Windows Vista.
2. Click Start, right-click Computer, and then click Properties.
3. On the Advanced tab, click Environment Variables.
4. Under System variables, click New.
5. Type MIG_UPGRADE_IGNORE_PLUGINS in the Variable name field.
6. Type IphlpsvcMigPlugin.dll in the Variable value field.
7. Click OK three times to close the dialog boxes.
8. Start the upgrade installation again.

Performing these steps should help you resolve the issues, if the Windows 7 upgrade is always stuck at 62%.