OwenBurton

Might be a bit much for one hard drive to handle. Consider an SSD for windows.

From a 1 TB to a 2 TB would be fine, it could take a while if it is full though as they are not the fastest drives in the world.

About 80Mb/s seems right for a regular Hard drive.
Size does not impact it that much, only the response time.
 

from this era you're likely to see intel GMA chips I believe. Hated those, if you think the original HD 2000 and 3000 are bad, wait till you try what they replaced. Intel has come  a long way as far as gpus go. 

Yeah, it doesn't need any external power other than that provided by the pcie slot. If you're really worried, you can grab a cheap evga power supply for 40 bucks that will be much more reliable than the psu in your system now, assuming it's some oem pos. Also, if you're really worried about bottlenecking, and can't overclock on your motherboard you could buy a Q9500 cpu for an extra couple hundred mhz. You should see better performance than your friend in games that really use the CPU, because even a fast Core 2 Quad can beat amd's apus.

So basically I have this pc that I've been using for at least a year now and I picked it up off of my mate. With this pc i've managed to play some not very demanding games like Gmod CS:GO and Cod Waw happily on low resolutions with the specs of 6gb ram, the core 2 quad and a radeon hd5450. Now I was wondering if I was to buy a GTX 750ti low profile would it be a useful upgrade and would it actually work with these components without being strained by bottlenecking. Thanks, Owen.

A few things to keep in mind about the GTX 750 Ti low-profile cards by MSI and Gigabyte:
-Both cards run hot. The Gigabyte runs hotter because it only has a single fan, but neither one is particularly cool in operation, meaning fan noise might be an issue.
-The MSI card overclocks like crap. With the right fan curves, I can get it Kombustor stable for 10 minutes at a time at +125MHz on the core, +600MHz on the memory. Go into Heaven or any game? Boom, insta-crash. I've got it stable at +50MHz on the core, +225MHz on the memory now, but considering how much juice it seemed to have at the outset, it's disappointing to end up there. The Gigabyte version supposedly overclocks better, but it runs hotter to begin with, so...
 
Now that I've knocked it, I'll give you the good:
-With settings on high, my MSI LP 750 Ti can handle Overwatch in 900p at 50FPS. Dial it down to medium or take the resolution down to 720p and I can get 60fps pretty easily. It's a surprisingly capable little card.
-It. Fits. Anything. Almost. It's a half-width card, which is great, but if you use the VGA adapter it becomes a three-slot card. The cooler takes up a slot below the PCB, and if you use the VGA adapter, you have to go above the PCB to mount it. Not an issue for me because I don't use the VGA adapter, but something to consider. That said, it's by far the most powerful half-width card available to US residents. Now, once that 950 makes its way over...
 
Overall, I really like the card. The overclocking shortcomings are a bummer, but it performs well enough without OC'ing to handle pretty much anything at 720p, with some settings reductions, at playable framerates, and can handle 1080p as well as any other 750 Ti.

whichever is cheaper is what i would say they both use the same chip on the inside. 

Yeah no problem, when you said gain a few extra pounds I, as an American, thought you meant gain weight XD, but then I remembered you're in the U.K.

You do realize that (1.) that would look like epic horse shit and (2.) I would have roughly half the GPU sticking out the side of 2/3rds of the case?!

Well, do you really look at your pcs that much? My pc already looks like horse shit, so I don't care that much. eh, whatever

Boom.
 
2GB, great OEM, no six-pin required.