Well, now you can, with Compact Alarmer, a free little application for Windows that simulates an alarm clock, with all of the options that you would expect.
The interface looks like the face of an analogue alarm clock, and there are two options for setting the alarm.
The first option is to select the exact time you would like the alarm to go off, and you can set the minutes and seconds. The second option is to choose in how much time, in hours and minutes, from the present you would like to have the alarm go off.
All of this makes Compact Alarmer a very useful tool.