nhuber,
I'll admit I'm making some educated assumptions here, but here they are. Considering you're looking to record mainly vocals and acoustic guitar, and that you have taken the care and the budget to spend a *minimum* of ~$1500 (new street price) for the guitar, you're not going to want to skimp on the front end of your signal chain; i.e. the business end of the recording.
While the advice about the room acoustics is good and correct, let's take it at face value that what you say about your room sounding OK is true. Add to that the fact that you're probably going to be using relatively close miking on both the guitar and the vocal, and we can assume that bass taps are not going to be your issue.
Of course, only you can determine that; if you suspect your room is limiting your recordings at all, then indeed you should take care of that.
But frankly, even if you had the perfect room, your current gear is most likely limiting you. For your instrument and intentions, I could not recommend the SM58 for either the vocal or the guitar (though you should still try it, because one never knows). Far more likely, you'd want to use the AKG and the Shure, probably on guit and vocal, respectively. The problem is, you have a real mismatch between the SM7 and the mAudio; the mAudio simply doesn't have the gain to support the SM7 very well. Sure, things can be adjusted in post, but frankly I'd advise avoiding having to do anything more than absolutely necessary in post for your situation. And also, frankly, I just don't consider entry-level mAudio as delivering the kind of performance your situation calls for. (IMHO/YMMV and all that, of course.)
That leaves you with the AKG, which is a decent mic, but that leaves you with only a single mic for guitar and vocal, where a minimum of two, and possibly three, are in order.
This is why I recommended the addition of another condenser of high quality without having to pay highway robbery price. The Mojave is just one mic that fits that bill. Then you'll want at least one channel of preamp that can not only properly handle the SM7, but deliver the quality worthy of both the AKG and the Mojave.
Of course monitors for quality mixing are a wise idea, but without front-loading the quality on the front end of your signal chain, they will be a waste of money; even with the best monitors in the world, if you don't capture a pristine recording, you'll never get a pristine recording out of the back end. Add to that, the amount of post processing you'll want to do to that guitar should be minimal; set the right levels and maybe - *maybe*, only if you need it - a small amount of quality compression, and that should be all you want to do to that sweet guitar. This mitigates the otherwise normally extreme need for mega-quality monitoring in mixing on your part.
So, just one considered opinion, other will disagree - some with respectful reasons, others not - so take it with due consideration and not as chiseled in stone. But I just wanted to explain what was otherwise an completely unexplained earlier post on my part.
G.