This video tutorial from OfficialTechTerry presents how to use your computer as an alarm clock.
Press Start menu button, then click Control Panel.
From the left pane choose Change to classic view option.
Double click Administrative Tools icon from the right pane. Now double click Task Scheduler icon. Choose Create Basic Task from the right pane.
Name the task and type simple description. Click Next. Choose when the task should be started (daily, monthly, weekly etc.). Click Next. Now choose what time does your scheduled task start (eg., 18:41).
Now click Next. If you want alarm to play some music file, click Start a program. Click Next and browse for music file that will be played when alarm starts. Click Next and Finish.
Close Task Scheduler window.
Your alarm is now set.