Pinkipad, you should click on Start, Run, "control userpasswords2" and determine which users have Administrator rights, you may need to use the NT Offline Password Editor software mentioned elsewhere on the forum to reset the Administrator account, and give yourself Administrator rights.
As to why Windows 7 asks for Admin rights its because Windows has became much more secure since Win 3.1! It now uses User Account Control to verify system changes that could have a undesired effects.