So I'm the resident Linux user now? :p
Anyway, I'd say to use what you're most comfortable with. A skilled Windows user won't encounter many headaches on Windows, and a skilled Linux user won't encounter many headaches on Linux. If there are additional requirements for the HTPC (IR remotes, full control via joystick, network and storage stuff), use the OS you have the most experience with.
I built myself small mini-PC solely for emulation with a lot of little requirements (auto-login, joystick-to-keyboard bindings, a game menu with icons, etc) and I would have had a hard time setting it up on Windows since I'm just not familiar with all the tools I'd need to do that.
Now about Dolphin in particular, just keep in mind that Linux builds don't have the D3D backend. OpenGL is fast and accurate though, so there may be little to no difference in performance. Test it to make sure if you're worried. Other than that, the Windows and Linux versions don't vary in terribly significant ways as it concerns ordinary users.
I can't speak for cooling, but the IGP (HD 4600 I believe, or something like that) on a 4670K should be more than sufficient for 2x IR in many games, and 3x IR in lighter, non-demanding games. It's a good option to save on costs, power usage, and generated heat. 2x IR is a little larger than 720p and 3x IR is a little larger than 1080p.
Anyway, I'd say to use what you're most comfortable with. A skilled Windows user won't encounter many headaches on Windows, and a skilled Linux user won't encounter many headaches on Linux. If there are additional requirements for the HTPC (IR remotes, full control via joystick, network and storage stuff), use the OS you have the most experience with.
I built myself small mini-PC solely for emulation with a lot of little requirements (auto-login, joystick-to-keyboard bindings, a game menu with icons, etc) and I would have had a hard time setting it up on Windows since I'm just not familiar with all the tools I'd need to do that.
Now about Dolphin in particular, just keep in mind that Linux builds don't have the D3D backend. OpenGL is fast and accurate though, so there may be little to no difference in performance. Test it to make sure if you're worried. Other than that, the Windows and Linux versions don't vary in terribly significant ways as it concerns ordinary users.
I can't speak for cooling, but the IGP (HD 4600 I believe, or something like that) on a 4670K should be more than sufficient for 2x IR in many games, and 3x IR in lighter, non-demanding games. It's a good option to save on costs, power usage, and generated heat. 2x IR is a little larger than 720p and 3x IR is a little larger than 1080p.