Prevent System Restore Point from being created during Install
UPDATE: Linking to similar content on serverfault.com. Remember that this takes you to information intended for system administrators. As a super user / power user, the below summary might be better.
UPDATE: Windows Installer 5 (available on Windows Server 2012, Windows 8, Windows Server 2008 R2 or Windows 7) now features a new property MSIFASTINSTALL which can be used to speed up the installation of a large MSI package. See the link above for valid values. I would suggest 3 for no restore point, and only FileCosting (the process of determining disk space requirement). Here is a sample:
msiexec.exe /I "D:\winzip112.msi" /QN MSIFASTINSTALL=3
It is also possible to set the DISABLEROLLBACK property to disable rollback support in the MSI installer. I would strongly advise against using this unless you are staging a fresh PC. This is a special case when you can just start over if something fails. For a computer in real use I would not recommend enabling this property.
The irony is that disabling rollback will speed up things the most if you are running a huge update package that replaces lots of files. It could be quite significant, but unsafe.