I run my main workstation as an ordinary domain user, but I frequently need to perform administrator tasks with it too. So here's what I do. I create a shortcut with the following target:
runas /user:domain\Administrator "cmd.exe /t:17 /k cd %systemroot%\system32"
Then I drag this shortcut to the All Programs | Startup folder on my Start menu. Then when I log on to my machine in the morning, a black and white command prompt window opens prompting me for my admin password, and once I enter it a new BLUE and white command prompt opens with \System32 as the current directory. I leave this command prompt running on my desktop so that any time I need to run an admin tool I simply type it into the command window, for example typing mmc compmgmt.msc opens Computer Management using admin credentials.
Of course, when I'm not at my admin workstation I lock the desktop!