your mileage may vary...
Hi there, tlitterio!
It's a really good question and there's been a lot of discussion about this in the forums. A quick search will probably turn up some great answers for you.
Everyone's work/personal situation is a little different, but in general it comes down to how many inboxes you have to manage and whether aggregating everything makes your life more or less complicated. I have everything in one system, but I work for myself out of my home, so it just makes sense. If you're not comfortable having your personal life co-mingling, as it were, with your professional life, then two systems are appropriate. So you're going to be the best judge of that.
Since you're just getting started I will caution you not to get too worked up over the perfect software tool. We've all (Can I speak in vast, obnoxious generalizations here? I think I can.) gone through bytes and bytes of software thinking we'll find the exact right product to speed us up or streamline the process or, I don't know, raise our children, but at the end of the day "perfect" is elusive. Even if it means having a paper-based system to get you started (and many of us do), don't let the tools hold you back.
OK, stepping off my soapbox (I carry this little portable one with me for occasions just like this...).
constant forward pressure