2009 Mac Pro as Gaming Rig?

Work is updating our Mac Pros and I may have the option of taking mine home for personal use. I personally own a 2011 Mac Pro, so I'm not really in need of a second Mac.

I was thinking of putting Windows 7 on it and installing a fresh SSD and more modern video card on it to turn it into a gaming rig, but I'm not sure if a 2009 Mac Pro (surely a beast in its day) would be able to keep up with newer games at 1080p resolutions (there's a good chance this would end up being a living room rig).

System Specs:

MacPro4,1

Processor Name: Quad-Core Intel Xeon

Processor Speed: 2.26 GHz

Number of Processors: 2

Total Number of Cores: 8

L2 Cache (per Core): 256 KB

L3 Cache (per Processor): 8 MB

Memory: 8 GB

Type: DDR3 ECC

Speed: 1066 MHz

NVIDIA GeForce GT 120 (**THIS WOULD BE UPGRADED**)

Type: GPU

Bus: PCIe

Slot: Slot-1

PCIe Lane Width: x16

VRAM (Total): 512 MB

Will that older, slower RAM be a big bottleneck? Is that processor still beastly enough to handle newer games? Am I a crazy person or idiot for even thinking this is viable? I've primarily been a console gamer, so I have no clue if this is even a good idea.

Thanks so much in advance for any help or guidance.