My opinion is that you need a decent interface. With a device that uses USB or Firewire, you can bypass a sound card. Then it becomes a matter of finding something with the features you need.
First, you'll probably want at least 2 XLR inputs with phantom power, simply because, if you get into it, you'll end up buying good mics that require the pw...and, for all I know, you may have one or two already.
Second, you'll want line-in jacks, whether on 1/4" or RCA to accommodate your drum machine, amp emulator, and anything else you're going to plug in that's not a mic.
Third, you will want one that allows you to listen to previously recorded tracks and the new tracks you are recording. This is called monitoring, and while you can use a headphone jack, when you get serious you'll find that you'll need real monitor speakers. So look for a device that has connections for an external amp or powered speakers.
It's also a good idea (but not absolutely necessary) to get something you can use as a control surface. A control surface is a thing that looks like a mixer that plugs into your computer, and controls the record, mute, solo, pan, playback, stop etc etc functions in your software. There are devices that combine control surface and audio input/monitoring, but they tend to be either lacking in features (i.e.: cheap) or overloaded with stuff for a beginner (i.e.: expensive). I used a Tascam US428 (now discontinued) for a control surface, but it lacked phantom power. You can buy an external pw unit (as a matter of fact, a friend just sent me one he wasn't using) but some of them are noisy. If you DON'T have a control surface, CEP allows using the mouse and keyboard (check out the shortcuts in Help) but that gets old fairly quickly.
All that said, I don't have any recommendations, since I use a more elaborate setup for mine, and I don't have any experience with the all-in-ones.
Two websites that are helpful:
http://www.adobe.com/support/forums/main.html which should take you to the Adobe forums: select "Audition" from the list of software. You'll need to register but it's not restricted to owners of their software (Adobe bought Syntrillium a couple of years ago, and renamed CEP Audition) and
http://www.audiomastersforum.org/amforum/index.php?sid=8d2aff3b63bb8071ad9a3831595ee7b0
Good luck.
