The so-called Anytime Upgrade can be used to upgrade Vista Home Basic, Home Premium or Business to the Vista Ultimate edition. It is in reality a new install and involves copying registry and other settings from the old to the new install. This fully automated process can take anywhere from 1.5 hours or longer. There have been many reports of upgrades failing at the last step ("Completing Upgrade"). If the upgrade fails, the system may rollback to the previously installed edition. While one might expect the upgrade process from one version of Vista to another to be painless- this is often not the case.

I have found the following suggestions helpful before performing an upgrade from Home Premium to Ultimate. However, following them is no guarantee of success. Also, If you applied a service pack to your current version of Vista, make sure your upgrade disk incorporates this service pack as well. The most current service pack is SP1.

After the install, re-enable the Windows features, software and hardware devices mentioned below.

Upgrade Preparation Steps

(1) Review Windows Anytime Upgrade FAQ. You may wish to run the Vista Upgrade Advisor.

(2) Create a full image backup of all hard drives using a tool such as Acronis TrueImage, Norton Ghost or DriveImage XML(freeware). Create the image on your Vista compatible USB 2.0/Firewire compatible drive. Create an emergency boot-up disk with all essential drivers and one of the aforementioned programs installed on it. Also, record your current version product key and make sure you have the current version install disk available in case there are issues with the image restore. If your computer was purchased from an OEM manufacturer such as Dell or Gateway, take the time to review what would be involved in an operating system restore using the disks and/or recovery partitions that came with your machine. Hopefully an image restore will not be required.

(3) Go to http://support.microsoft.com/kb/946078. Per this knowledge base article, uninstall the following Windows features:

(4) Turn off all unnecessary USB peripherals (scanners, USB drives, etc.). Vista frequently has issues with USB host controllers & devices such as external USB hard drives. This step is an attempt to prevent USB related issues during the upgrade. In addition:

(5) Turn off anti-virus/anti-spyware/non-Windows firewall software.

(6) Run MSCONFIG from Accessories > Run program.  Disable loading of all startup items.

(7) Set sleep power settings to 'Never.'

(8) If your graphics card manufacturer's supplied video driver is not WHQL certified, then consider uninstalling and reinstalling Vista's standard video drivers. Even if it is WHQL certified make sure it has been running stably on your system for an extended period. Nvidia drivers are notorious for their instability.

(9) If the Vista DVD was burned from a downloaded ISO file, run a CRC check to verify that the image is correct before burning it to DVD. Then verify the DVD after the burn.

(10) After completing the above, reboot and wait for Vista to fully load. Then insert the Vista upgrade/full version CD and click on setup to begin the upgrade process from within your current version of Vista. Be sure to have you new product key available for reference during the install. The setup process should prompt for applying system updates and will run the compatibility analyzer. Also, be sure you select the 'Upgrade' option. The only other option may be a fresh install- which will require you to reinstall all of your programs, emails, etc.

(11) After the upgrade is complete test all installed applications (productivity, anti-virus, disk creator, etc.). If a particular application is not working, then consider a repair or reinstall of that application. Just because the upgrade completes successfully does not necessarily mean that all programs function correctly. Pay particular attention to anti-virus programs- these may still appear to function properly, but a corrupted install may cause system instability/crashing. In addition: 

(12) After the above, re-enable Windows features, software, devices, etc. disabled in steps (2)-(8) above. Test any hardware that was re-enabled for compatibility and stability.

Note: Other then Step (3), all other preparation steps are optional, but may increase the probability of a successful Upgrade. Also, do not attempt to upgrade a machine that has hardware and/or software related stability issues that may, for example, be uncovered from step (4) above.  A good resource for helping determine the cause of Windows stop messages that may be related to hardware and/or software problems is: http://aumha.org/a/stop.htm.