It's a langauge barrier thing. He's in Rome. A service is a program that can start every time your computer starts, not in your user context, but in a system context. Therefore some of its functionality is available to the system at anytime. I haven't installed any of this yet, but looking at the arcsoft website it says that it supports Canon RAW, so installing a codec to support it in windows if you are going to use arcsoft's functions might be an unnecessary step. The codec may be useful for other processes, but if you call into a piece of code that already has a library to support the format, that codec may never be used. I'm not about the specifics of this app though.
BTW, thanks for the thread, I'll be installing something here in the next week.
FYI, the first link is throwing page not found for me: http://software.canon-europe.com/software/0026049.asp