I might be talking out of my arse here - as usual -but doesn't Windows 8 give you the option of installing Windows 7 anyway?
Tonar, the gtx460 you are running now is more powerful than a GT610 card.
I just did a quick check of NewEgg and as long as you screw it all together yourself - for just over six hundred bucks you can get an AMD 760K cpu. Thats a quad core running at 3.8ghz. A Gigabyte mobo to stick it on, a 1 TB hard drive, 8 gigs of DDR3 memory, a 600w power supply, a case, a DVD drive and an Nvidia 7600gtx.
Re-use keyboard, mouse and screen but operating system will be extra.
This system will run CLoD, RoF and BoS on pretty much max. without any problems at all.