Using git on Windows has historically not been super fun. The CLI installer mostly works, but it's pretty clunky. Cygwin works fine too, but it's also not especially elegant. At the very least, known of these solutions conform to the expectations of people of the platform. The GUI clients on Windows last I looked (a year ago) were pretty terrible, especially compared to TortoiseSVN, which isn't bad. OS X, on the other hand, had several very nice GUI clients even before the official Github client came out.