Running as a "Standard User" will also prompt for Adminstrator credentials
(Password and OK to continue). In Administrator mode you are only asked to
continue.
UAC (User Account Control) checks each application you open as to whether
or not the application has "administrative rights' - many of the programs
created initially for XP and some for Vista (Those not certified or signed)
do so. The applications use administrative rights to make changes,
deletions and/or changes to system files and locations such as the registry
Most malware (99%) piggy back on those applications to install themselves.
Anytime you attempt opening such an applictaion,UAC locks the desktop (dims
the desktop) so changes cannot be made unless you allow the application to
run.
As more and more pplications are writen and cerified/signed you will see
less and less requests from UAC. Havind an extra mouse click is certainly
worth the malware/spyware protection.