Recommendation for Video Cards

[nak]

I am new to this Forum, but have played the entire series of Penumbra games. I have two desktop computers that I know will not run Amnesia due to the current Video Cards (Chipsets). I am very good with understanding software and general computer issues, but am terrible at understanding the Graphics. I would like to buy a new Graphics Card (and most probably will need a Power Supply), but after reading all the issues here in the Technical Section I am truly at a loss at which ones will work the best for the dollars. I don't want anything fancy - - just want to play the game. Here is the Computer I need to purchase for:

CURRENT CONFIGURATION:
Make & Model: Acer Computer Aspire M3900
Operating System: Windows 7 Home Premium 64
Intel G45/G43 Express Chipset, Video BIOS 1666.0
1360 by 768 Graphic Mode.
3.20 GHZ E6700 Dual Core Pentium Processor
6.0 GB of RAM

The Computer has available one PCI ExpressR x16 slot and one PCI ExpressR x1 slot in it (not being used).

I see a lot of Cards on sale for between $60 to $100 and would like to stay in that range. Can anyone recommend a few decent Cards that will work and the proper Power Supply??