Lets check the system requirements:
� Microsoft Windows XP or greater
� A computer that has a 1.4 gigahertz (GHz) processor
� 256 megabytes (MB) of system RAM
� A hard disk that has at least 2 gigabytes (GB) of available space
� A 32x speed CD drive
� A 64 MB video card that supports Hardware Transform and Lighting
� An audio card and speakers or headphones
� A Microsoft mouse or a compatible pointing device
� A 56.6 kilobytes per second (KBps) or faster Internet connection for online play
� DirectX 9.0c
As you can see, this minimal requirements are not big deal for today computers, and with the PC that you have you'll be able to play the game just perfect, and maxed out.
AOE 3 doesn't need an extreme computer, and also with those specs that you have, you'll be able to play even greater games, so don't worry about it and go ahead and install the game and have fun playing it.