Help with GPU and PSU replacement

[StateSheriff]

Hi. I am wanting to replace my GPU and PSU for my Dell Studio 540.
GPU: http://www.amazon.co.uk/gp/product/B009KFT1ZG/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A3P5ROKL5A1OLE
PSU: http://www.amazon.co.uk/gp/product/B009RMP2VE/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A3P5ROKL5A1OLE

I just have a few questions about compatibility. I've only ever opened my case up once, to replace the GPU with a 9600 GT, which was pretty easy. I decided to open it again and (try) to measure up whether the new GPU and PSU mentioned above will fit. I'm still not sure if they will, since the dimensions are a bit confusing, especially for the PSU I'm a bit worried due to the huge fan sticking out below its slot. See the pictures below:

http://i.imgur.com/mAc47AF.jpg
The PSU is on the top left (I removed the GPU temporarily, normally bottom left.) I'm worried if the PSU will be able to fit in or not. This picture will help with another concern, the GPU. My current card takes one slot, but the new one seems like it takes two - However where you slot it in, there are metal things separating each slot, so I have no idea how I'll be able to get it in there/If the metal separators can be removed?

Secondly, I decided to try and remove the PSU to see how easy/hard it is, but I couldn't do it at all. Picture below is the back of the case, the top part is where the PSU slot is:
http://i.imgur.com/h2E7bDq.jpg

Any help and reassurance would be appreciated here!

 

[StateSheriff]

I have no idea why the fan is mounted like that.. I haven't touched it since I got the PC.

 

[StateSheriff]

Also, I took a picture of the slot for the GPU.
http://i.imgur.com/GKGugXZ.jpg
I removed the metal covers for each slot, but you can see the metal dividers which can't be removed and are part of the case.
http://imagenes.pccomponentes.com/gigabyte_geforce_gtx_650_ti_oc_2gb_gddr5_1.jpg

As you can see, it doesn't look like there's any way it can fit within the slots?

 

[StateSheriff]

Okay, thanks for the help! I know my questions are a bit silly, I'm inexperienced with most of this.

So I won't have any problem fitting the PSU, what about the GPU? My current one is a 9600 GT.
http://i.imgur.com/mAc47AF.jpg
You can see here on the bottom there are some connections on the bottom-right, I need to make sure the new GPU won't restrict them because I guess that'd be a real pain in the ass.

 

[StateSheriff]

I don't think so, but it all depends on the length of the GTX 650 Ti and how far out it will come.

 

[StateSheriff]

Where did you find it was 250mm in length? I can't seem to find accurate dimensions for this GPU.

Also, can someone tell me the difference between these cards?
http://www.amazon.co.uk/Gigabyte-NVIDIA-GTX650Ti-PCI-E-Graphics/dp/B009KFT1ZG/ref=sr_1_1?ie=UTF8&qid=1385809773&sr=8-1&keywords=GTX+650+Ti
http://www.amazon.co.uk/EVGA-GTX-650Ti-Graphics-Card/dp/B009O1UOTS/ref=sr_1_6?ie=UTF8&qid=1385809773&sr=8-6&keywords=GTX+650+Ti
http://www.amazon.co.uk/Gigabyte-NVIDIA-GTX650Ti-PCI-E-Graphics/dp/B009KFT2KA/ref=sr_1_5?ie=UTF8&qid=1385809773&sr=8-5&keywords=GTX+650+Ti

I don't exactly understand why the one I plan to buy is double the size in length?