Thanks for all of the comments guys you has been really helpful!
I have decided that I will buy an iMac if I can sell my current computer for a decent price. Its is only a few months old and has only been used for basic tasks so far so it hasn't been punished quite yet. I should be able to recuperate most of the money I spent on it right? It is currently set up a custom workstation, silent high quality components, sound proofing, lian li pc case and the specs below. I don't know if people have been able to sell new pcs well on ebay as there is not a big market or specific category to sell pc's in as if it would be for a specific product. People build and sell for a profit right so I can't see why I can't recuperate most of the money.
As for the decision I have mainly chosen an iMac because of osx. I just think it is a much more slick and pleasing os to use compared to windows, just a shame it is so much more expensive for what you are buying. My other reason is because of the high quality components in a sleek package with an amazing screen so it ticks most of the boxes here. But there are only three different options for desktop users which is quite limiting. Some more downsides are lack of upgradability, serviceability and life expectancy. If a windows machine had the same quality components as an iMac the mac would fail first as it runs hotter so will fail sooner.
So basically if I am able to sell all of my current pc and stuff for a decent price iMac it is. If not the decision is made for me and I will use win7.
Lol the OP is obviously set on an iMac. Just buy the iMac. You will probably kick yourself 3 years down the road for buying it, but then you only live once...
It is down to price now, I was open to both before.
I dont know about the new imacs but here is a review of the 2011 27 inch.
http://www.anandtech.com/show/4340/27inch-apple-imac-review-2011/7
The dell u2711 is also in the comparison its very similar to the 27 inch imac.
Any professional monitor (the really expensive ones) are going to be much better than the imac monitor.
Note: Im not talking about the upcoming models, just the current ones.
They may be better at presenting accurate colors but the apple screens are far more pleasing to the eye, which in the end of the day will mean a more enjoyable user experience. For most professional monitors they are set up for there actual light conditions at hand, so a bright as a desktop surface during daylight hours. This is a totally different application so will pale for doing general tasks. Looking outside of iMac nothing is coming close to retina for pc users right now.
I have one very old Laptop running Windows 3.1. one Pentium 4 that's now ten years old and one Dell Laptop running XP now 8 years old. All are more than serviceable though the Dell needs a new battery. I work with colleagues many of whom have Windows PC's between seven and ten years old and all have been faultless. Given the above it begs the question - what the hell do you do with your tech that it only lasts such a short time?
Lower life expectancy is to be expected but the iMac's are quite recyclable so just make sure you to take it to a recycling facility when it dies. Mine just has to last 3 years without fail until my masters ends. After then it will be a redundant machine and it will just be used as a tv or for low level pc work. If I was to keep using my current pc I would be less inclined to keep it in three years time. I would either sell it for very little or it would be put in a corner due it's cluttered appearance cables ect.
Really the iMac should be more like the mac mini. You should be able to open it and change parts. This could easily be done now as the new iMac contains so little part and it less complex. Apple just wants you to buy new like the iPhone's upgrade culture. This should not bleed through in to pc's as well. Disappointing Apple. What is the point of a more sustainable computer when it can't be designed to have a more sustainable service life.