Unless you're going to overclock, I suggest getting the 3570k because it's newer and consumes less power. For a video card I would get a normal GTX 550 Ti if I were you or a 2gb edition which will help in games.
Check your PSU is enough for the components before buying them.
Are you suggesting that i get i5 3K series as well as a GTX 550Ti. Pardon me but i did not get the 2gb part.
My current PSU is generic (mediocre); i have to replace it!
Yeah, get the i5 3K and the GTX 550 Ti. The 2gb are if you want better "performance" (it helps with textures and high resolutions) in games. As you can see from the links there is a 550 Ti with 1gb memory and one with 2gb.
For a PSU I recommend the TX650 from Corsair. It'll allow you to sli your 550 Ti if you ever want to in the future providing that your mobo supports it. It also has 80 plus bronce efficiency and corsair is a good brand
The 2500K and 3570K should be relatively close in price.
The 3570K will be a faster processor when not overclocked. It starts with a higher multiplier, and the instructions per clock is 5-10% more efficient.
If you really will not overclock, look at the cheaper 2500 and the 3570 chips.
That said, for the small price premium, I would preserve the option to OC with the "K" variant.
I suggest you get the 3570K and try the integrated graphics first.
It should be fine for everything except fast action games.
Even then, at 1440 x 900, you should find most games playable.
If you find your games want more eye candy, or higher FPS, then you will have a better idea of what discrete graphics card you would need to add.
I would recommend sticking to just buying the 3570k - I checked some benchmarks for HD4000 (here) and it seems to be perfectly capable of doing Crysis 2 (which is a bit down the page) at playable frame rates at medium settings around your resolution. As geofelt said, if you find yourself in need of more horsepower, you'll still be open to any video card (whatever's new whenever that time comes). On the whole, this is the more affordable option, which is why I suggest it.
I would highly recommend, if you go the Ivy Bridge route, to NOT get a different processor than the 3570k, as the only other quad-core i5 with HD4000 is the 3475, and I can't find anywhere that sells it currently.
Should you decide to go for the 2500k, the 2500 vanilla or even the 2400 should also be solid options, since you've said you don't plan on overclocking. As far as video cards are concerned, I've quickly rounded up a few solid cards across your budget:
You can have both HD4000 and a discrete card enabled at the same time, however you cannot do anything like SLI/CrossfireX with them (ie, use them together for one task).
What you CAN do though, is have each of them working separately - that is, have each outputting to a separate monitor. Whether or not you can run them both on one monitor and do video editing with HD4k and play Crysis 2 on a discrete, that I'm not sure of.
Put simply, SLI/CrossfireX is exactly what you want to do: have both GPUs working together on one task. SLI and Crossfire are two different technologies, but they produce the same result (for the most part). SLI is for Nvidia cards, and CrossfireX is for AMD cards.
So unfortunately, there's no way to get HD4k and a video card working together the way you want it to.
i do not want to multitask / or use two screens. i think you said it correctly that it can not SLI / Cross fireX (i need to google what it means).
By using them together i meant combining forces to do one thing i.e. using HD4000 + GPU for editing.
Or using them together to play games.
That being said, one thing a time and on one monitor only.
With the newer Z77 chipset motherboards, there will be a virtu capability which will use the most appropriate graphics engine for the task. The HD4000 for static non intensive work, and the discrete card for high fps work. in fact, it will use both at the same time to smooth out monitor response. No big jump in fps though.
Research virtu for more info, that is all I know about it.
Unless you are an avid gamer in search of maximum FPS, or are into triple monitor gaming cf/sli is not necessary.
Today's top end single cards will be more than enough, and they will only get better in thr future generations.
If you ever need more, just replace the card you started with. A quality 650w unit will run any single card out there. Future cards will take less power as the manufacturing technology gets even smaller.