Can my compact PC be upgraded with a graphics card? What is the cheapest to play these games?

[CRT dude]

I would like to Play Dark Souls at locked 60fps & max settings on my PC & I would like to know which graphic cards I would need to do so & if it can be compatible with my system. Specifically, what is the absolute cheapest card to get that performance.

This is my PC:

http://panam.acer.com/acerpanam/desktop/2010/acer/Aspire/AspireX1301/AspireX1301sp2.shtml
and a review of it
http://www.pcmag.com/article2/0,2817,2362960,00.asp

• 
  Acer Aspire X1301
  Processor: AMD Athlon II X2 215 Processor 2.70 GHz
  RAM: 4.00 GB DDR2 (out of a max 4 GB)
  Windows 7 Home Premium 64-bit (6.1, build 7601)
  Graphics card: Integrated NVIDIA Gefore 9200 (256 MB).

I opened up my PC case & everything is so crammed & I couldn't even separate where the graphics card was located in.
The PCmag review said this:

"and don't even think about adding discrete graphics cards, there is absolutely no room."

Can I just buy a cheap graphics card & swap it out? Would I have to buy one that is specifically small so it would fit?
I never changed anything in a PC ever. If I swap a graphics card will I need to replace the power supply as well? Will I have to reinstall Windows or download drivers before hand to be able to access my PC?

 

[hemantgta]

please upload a screenshot of ur pc's cabinet. if there is enough space then there will be a chance.
u can go for hd 6670 1gb ddr5(85$) or hd 6670 2gb ddr3(65$)or hd 6570 1gb ddr5(62$)

 

[CRT dude]

please upload a screenshot of ur pc's cabinet. if there is enough space then there will be a chance.
u can go for hd 6670 1gb ddr5(85$) or hd 6670 2gb ddr3(65$)or hd 6570 1gb ddr5(62$)

Here are the pictures:
http://i3.minus.com/jbwbKnJo4aMqD3.jpg

http://i4.minus.com/jboSlCNlTqlQ9L.jpg

The left side is the front of the PC, the right side is where the back of it that I connect the cables to.

Would I need a new power supply for any of those graphic cards as well?

 

[CRT dude]

What matters more for max settings & 60fps?
2GB with DDR3 or 1 GB with DDR5?

 

[CRT dude]

Ok I did some digging around & I found out my PC can only accept low profile graphics cards AND has to be compatible with a 220W power supply.

Some other people listed these graphic cards as the ONLY ones I can use:

-Radeon HD 5450.
-Radeon HD 5570.
-Radeon HD 6570.
-Geforce 9500GT.
-Radeon HD 4350.

Better ones that are not compatible with the power supply, but people still recommend to use because they would still work?
-Radeon HD 6670
-Radeon HD 4650
-GeForce GT22

Those posts were a few years old, is there any other low profile cards graphics cards better than them with a 220w power supply?

Can any of them run Dark Souls at 60fps with lowering any settings? I wouldn't mind play at a 1024x768 resolution to get a better performance.

 

[hemantgta]

u could buy a hd 6570 1gb ddr5 gpu .but i dont think there is enough space for hd 6670.
dark souls will work perfectly with hd 6570 1gb ddr5 at 1366X768 with med-high settings.
enjoy mate.

 

[hemantgta]

What matters more for max settings & 60fps?
2GB with DDR3 or 1 GB with DDR5?

ddr5 is 15%-25% better than ddr3 so yes 1gb ddr5 is better than 2gb ddr3 .