The 2500K is a solid sweet spot as far as processors go, I would stick with that.
The corsair H100 cooler is simply overkill unless you are shooting for big overclocks. Either use the stock fan or if you insist on an aftermarket cooler, go with a Hyper 212+ for around $30.
You won't need an 850 watt power supply for this build. Honestly, you won't even need 500 watts for this build. I would seriously look at something in the 600 watt range and that will give you room to expand down the road. My PSU preferences are Corsair, Seasonic and Antec.
16GB of RAM is overkill too. Unless you are getting it insanely cheap, I would go with 4-8GB of RAM instead and use the saved money to put towards an SSD which would make a far more substantial improvement.
If you intend to simply move the hard drive and put it in another box and have it boot right up and work, prepare for some problems. There will be tons of driver
changes and such for the mobo, activiation of the OS will need to be performed again, etc. I would never in a million years just move a hard drive from an old box to a new box. Always start with a fresh clean install of the OS and build from there.