Небольшие рекомендации и комментарии по "железу"

CPU:

x86 processor such as: Intel Pentium 4, Intel Pentium M, AMD Athlon XP/64, AMD Opteron, or newer CPU (that support SSE. Anything made in the last few years does.).

If your GPU/VPU does not support hardware video decoding then you will require a fast modern processor is required to decode some videos (H.264, VC-1, etc) in 1080p.
There is very limited Power PC (PPC) support

RAM:

Minimum: 256MB
Recommended: 1 to 2 GB or more

Graphics:

XBMC will run on most graphics cards made in the last few years, including hardware video decoding support. This includes most cards from ATI/AMD, Intel, or NVIDIA which support OpenGL 2.0 or later.

Minimum without HW decoding:ATI Radeon RV710/M92 (HD 4300/4500), Intel GMA 950 (945G), Nvidia GeForce 6-Series
Minimum for HW decoding: ATI Radeon Cedar (Radeоn HD 5400 Series or newer, Intel GMA X4500HD (G45) or newer, Nvidia GeForce 8-Series or newer

Video decoding:

For hardware video decoding, which may be necessary on low-performance CPUs to playback 1080p content, make sure your GPU or VPU supports either VAAPI, VDPAU, OpenMAX, or CrystalHD.

HDD:

Minimum: 4 to 8GB
Recommended: 16GB or more