If you want to try something cool, try Crimson Editor.
I use WinSyntax, and in total have written at least 50 000 lines of code so far with it, and it allows a very cool trick allowing easy creation of redundant code, but it has no window splitting. No window splitting is actually good for C though, it encourages you to make prototype headers etc (two files). It also forces you to keep your file sizes down, so you code modularly etc..
But anyways, my recommendation goes to Crimson Editor. ConTEXT is fine too, except it screwed up my notepad on my system