How much would it take to upgrade graphics card? Specs are below: D?

So my brother broke my laptop and i wanted to get a gaming pc anyways and my parents agreed, so i was going for an alienware, literally so close in grtting one but i decided not to after a lot of people warned me not to get one, I then looked at custom built but i have no idea what to put for like motherboard and power supply etc. So one of my irl friends told me they had got a zoostorm computer and i've seen them before but didn't consider it since i had no one to tell me what they were like and when my friend told me i was considering it. So on argos i found one with an i7 4770 3.4Ghz, 8gb, 1Tb but it has an intel hd 4000 and the others which did have a gaming graphics card were around £800-£900 so i was wondering if i get the one with intel hd 4000 and upgrade the graphics card but i don't know how much it costs and where you could upgrade it. Also i want to be playing pc games like Minecraft and sims, left 4 dead etc and i have a youtube channel too which i would like to upload on since i found a great community of people who i have talked to on skype for almost a year now.

Added (1). http://www.argos.co.uk/static/Product/partNumber/2278201.htm This is the one i'm considering to get, it says graphics performance built into processor, so would that be changeable

Guest

The one with the intel hd 4000 card isn't really made for gaming so I'm guessing it is cheaper than the the 800-900 pound. If thats the case then I would go for the intel cause it is usually onboard which means you can put another graphic cards on. It also makes it easier for you sinds you can choose what kind of graphic card you like and how much you can spend on it.

Mid range graphic cards for example are usually around 200 pounds which can run most games with high graphics.

If you're planning to use your graphic card in a long run then I suggest to buy a card that has high specs which usually are a little expensive (around 400-500 pounds). Because games are going to improve over the years which means you need a better graphic card to maintain those graphics and performance.

Hung

That is a pretty good computer for the price. You just need to add the graphics card look at videocardbenchmark under highend gpus to find the best performing one for your budget since you'd be surprised that a lot of amd or a lot of cheaper cards can be better than the gtx 750ti you are looking to get.

Edward