I'd recommend "Is There a God?" by Richard Swinburne for the best argument answering "yes" I've ever seen.
It doesn't convince me for a variety of reasons, and in fact some other people I've read do a better job (e.g. Plantiga on God as a necessary being) but it's a good slim volume.
The case for a "being" that is the foundation of existence is hardly the same as the case for a space jellybean. "Being" is in quotation marks because God isn't just posited as one more object in the universe; his existence is qualitatively different than that of objects in the universe. The theist believes that it is necessary for God to exist; that is not possible for him not to exist; and that in every possible world you can imagine, there is a God, and the same one. God isn't a substitute for science; rather, God is the explanation of why science explains.
I'm still an atheist, because I think that nearly all of the theists are as flippant with atheists' arguments, which they fail to really tackle, as your average Internet atheist is with religion. At the end of the day, the null hypothesis wins a tie for me.
So anyway, JP, I'm on your side. Not because I think you're right, but because I think people are overly dismissive of the philosophical case for God nowadays. Richard Dawkins (who I think is right, in the end) is absurdly out of his depth when it comes to discussing philosophy.
ps: For what is, to me, the best analysis of the ultimate question of philosophy or what-do-you-call-it, I'd recommend the chapter "Why is there something rather than nothing" from Robert Nozick's Philosophical Explanations. It's an essentially atheist take on the same issues that lead many to believe in God, but one that never, unlike some popular science writers, begs the question ("the ultimate answer to why the universe exists is STRING!") or just says "we can never hope to know, so let's not talk about it."