What could I possibly do to make this computer decent?

TestOne

Honorable
Jun 20, 2012
146
0
10,680
I own a HP Pavilion a6763w, and when I first got it ( A year ago) I added a Galaxy GT 440.
7GB ram.
AMD X4 @ 1.8GHZ (Main bottleneck)
I can play GTA IV, medium settings at 30FPS. Some slow downs when there are over 50 cars (Typical in multiplayer).
I experience quite a bit of performance hits randomly, and I am fairly certain my processor is an evident bottleneck.

I am hoping upgrading is as simple as:
Upgrading PSU to 450W
Replacing the AMD with
http://www.ebay.com/itm/AMD-Phenom-II-X3-740-3-0GHz-Black-Edition-Triple-3-Core-Processor-HDZ740WFK3DGI-/140773250361
Also adding this for high power GPUs
http://www.newegg.com/Product/Product.aspx?Item=N82E16817104054&Tpk=fsp%20booster

So, with these two things, what video card is suitable? I was hoping to upgrade to something like a GTX 560 FERMI.
Something along the lines of
http://www.newegg.com/Product/Product.aspx?Item=N82E16814500241

However, the length may be a bit of a problem.
My current GT 440 is 6 inches, it has about 3 or so inches before it hits the drive bay.

I am hoping someone can help me solve all of this. Also, I am aware that the price will be around 300~400 dollars total. It is much cheaper than building a new computer, even if the performance increase can certainly ravish the current build. I am aware my ram is DDR2, and I am familiar with custom builds. However, I am currently seeking to just drop a few hundred to breath some life into this little box. Also, cooling is not a problem. My current board temp is 40c~ cpu is 28C~ and my GPU goes to about 38C full-load while running GTA IV.

Again, I am not looking to run games on ultra or high, and I definitely do not use anti aliasing. I wish to run my GTA IV on maybe high, with the view distance at around 40. It is the most demanding game I play, as most of my games are source based. Currently, anything better than my GT 440 would be great. Thanks.
 

TestOne

Honorable
Jun 20, 2012
146
0
10,680
As I mentioned, I already know the benefits, but I actually don't want to do that at this point in time. Later on, that may be an option;however, I am looking to do a quick fix for right now.

Not only will it be 60% cheaper, but it will give me what I currently desire.