Now that Vista SP2 is being pushed out via automatic updates I will share some lessons to avoid 0xc0190036  error:

Don't let it install automatically - I shall explain why in  a bit. For now switch automatic updates to "Manual" or "Download Only" so that it does not kick off until you have done the following:

1. Run checkdisk on the system disk
2. Run it again
3. Uninstall your virus scanner
4. Backup
5. Make a restore point
6. Reboot
7. Run the Upgrade

Failure to do this can cause problems if the file system gets corrupted and or isn't consitent hence the checkdisks.