technically it's still possible to get rape.sh working on windows, but it would take all day to walk you through it (google cygwin if you really want it).
what i suggest is that you simply download some LiveCD that comes with curl and boot from that temporarely (bonus points for not leaving any traces on your pc either)
i like the ubuntu livecd, but iam unsure if it has curl and there are probably much better ones available. you can check em out here:
http://securitytools.wikidot.com/linux-hacking-kits
everyone is talking about backtrack (although i'm not sure if it's because they're kidding), so i'll mention that one too.
http://www.remote-exploit.org/backtrack.html