It seems like you're really on the right track!
Have you tried to install the gem libcurl? I suspect this may be your problem.
To follow up on your post, I read an article on StackOverflow with someone who had a similar problem installing libcurl on windows. The article was entitled something like: install-ruby-curb-gem-in-windows-xp
It seems like the responder to the StackOverflow question wrote a blog which solves the windows problem step by step. Unfortunately, I cannot post link yet, so I put all the links you need in a pastebin file (one to stackoverflow, the other to his blog post). This is going to be really confusing... Sorry.
Here they are: pastebin . co m /zHA7S2zR (remove spaces)
Hope this helps!