Also, remember that each request is actually not running in parallel. (for example, the css can not be retrieved until the html has been received by the client and parsed) Also, each of those parallel requests have their own overhead (connection, server response time, then downloading)

So while intuitively, the parallel request seem like the faster option, it's probably likely in this case, that the single page in-lined option is optimal. (Even at the expense of ever so slightly more bandwidth)