Good ($100-175) video card for Asus M4N68T-M board

[apositive1]

Hello,
I have an Asus M4N68T-M series mother board that I would like to add a video card that has an Nvidia chipset on it. I have 400-450 watt power supply, but I don't mind upgrading if necessary. I am really happy with the system performance, just need to get away from on-board video to be able to do some gaming. (Skyrim)

Thanks!

John

 

[apositive1]

I forgot to mention that the motherboard manaul states that it has a PCIex16 slot.
That is what I plan to use for video card. I'm assuming that's PCIe 1.0.