New system has low performance, looking for advice.

That GPU is a Utter Crap.
It is not meant to even Run Games.

You atleast need a 6670 to Run the Games.

Both GPU and CPU are not the strongest.

Suggest you look for published frame rates for the fx-4100 and hd5450 and see if you are worse or roughly the same. I suspect that you are already getting all you can from the home theater (not gaming) video card and the not-real-good for gaming CPU.

Look at the last pages of these two articles to see ratings of CPU and video cards. Find your cpu and gpu and see what's stronger. Video cards are very easy to replace and will have the most gaming impact. CPUs are harder, especially if you needed a MB swap.

http://www.tomshardware.com/reviews/gaming-graphics-car... video
http://www.tomshardware.com/reviews/gaming-cpu-review-o... cpu

The FX 4100 is fine for a mid range gamer

But as suggested the radeon 5450 is not a gaming card . Its more for playing DVD's
You dont say what kind of power supply you have , but if its a decent 450+ watt unit you should be able to drop in a Radeon 7850 for about $170 and then game very well

Thank you for all the information.
I will look into getting a new GPU ASAP.
I have a 500W PSU, so I will have a good look at the Radeon 7850.

Yeah Radeon 7850 is a Real good Deal.  

I have the same processor and a Radeon 6950. I get good frames on high settings on all of the games that I play.

I'd leave the CPU and grab the 7850 (I was going to buy this card) if I was you. Just be sure your PSU has a 6 pin PCIe connector, or you have two molex connectors free for an adaptor.