Usually I'm the only one pushing for
Lcc-Win32It's small and fast, has a nice IDE with code completion and lots of features like a built-in debugger, a resource editor, profiler and some other useful things. It also provides some "extensions" to ANSI-C, like operator overloading. I don't know how close it follows the C99 standards, but stdint and bool, aswell as C++ style comments are supported.
However, the best thing about it is that it takes about 5 minutes to download, install and start coding (if you're not on a dial-up connection that is). The whole package including the compiler,IDE, Win API docs and C standard library docs gives a total of 20 Mb and the Windows API documentations stands for about 13 of those, so if you can do without it you're home free with a download of less than 8 mb.
And, I almost forgot
Open Watcom, but that's a totally different story [smile]. It's a nice compiler/IDE loaded with features but might be to much to grasp if you're a newbie + it doesn't include the Windows platform SDK, only a skeleton implementation of it.