Its actually a really bad idea to base stuff only around a single brand, you greatly limit your options and cant shop for the best deal. An XFX only build will restrict you to using either an old nVidia card or an AMD card, XFX also no longer makes motherboards so you would be restricted to using either an old LGA 775 motherboard or an AM2+/AM2 board, both of which are several years old and not good values or good choices for a build today.
If you want an i7 the closest you can get to building around XFX would be to use an XFX graphics card and power supply, they dont make anything else for an i7, and two parts from one company is far from building around them in my book.