Why is my game not installing?

[animetoons]

I have Vista, I am trying to install my game with minimum system requirements of: Microsoft Windows XP/2000; Pentium III 800mhz or Athlon 800Mhz or higher processor; 256MB RAM; 3500MB of uncompressed hard-disk space (plus 400MB for Windows swap file); 100-percent DirectX 9.0c-complaint versions of the following (including drivers): mouse, keyboard, 4x DVD-ROM, 32MB video card, and 16-bit sound card.

I have: TOSHIBA: Satellite A205, Intel(R) Core(TM)2 Duo CPU T5550 @ 1.83GHz, 3.00GB RAM, 32-bit Operating System. And lastly Windows Vista(TM) Home Premium.

Also my game will not download before it can even begin. After I made the first basic choices (agreements, where would you like to save this file, ect) a window pops up saying that my "system has not been modified" and that I should install again at another time.

WHAT IS HAPPENING!?!?!?!
And how can I fix this?

 

[Zoron]

It really helps when you specify what game you're trying to install.

 

[ohiou_grad_06]

I know on like medal of honor, pacific assault when I wanted to play that, I had to navigate into the cd, find the setup file, and right click on it, and tell it to run as administrator.