> Are you planning on using a keyboard controller for soft synths?
Umm, maybe? I have no earthly idea, lol. I'm an utter neophyte when it comes to all this stuff.
In that case, I'm going to rule out any interfaces without MIDI I/O. The cost difference is negligible, and if there's even a remote possibility that you'll use it in the future, you don't want to be replacing your interface in 6 months when you realize you need it.
I'm downloading Cakewalk Pro now and I'll check it out. If I understand it correctly you run the guitar through an interface and into the software where you can record however many inputs the interface is designed for?
Got it in one.
Here is a 2 channel interface with MIDI in/out. This was my first interface, and I credit this purchase for my entry into audio production. It's easy to get good sounding recordings from this thing. I later discovered that it's because the Presonus preamps are crazy hot. It's like running a saturation plugin all the time, or a nice tube amp. These things are $99, and while not the best interface on the planet, they're $99 and can still make a great recording.
I tend to like Focusrite preamps because they are a lot more transparent, but in order to get MIDI I/O, you are looking at $219 for the 2i4.
At $150, you have a LOT of choices:
Steinberg UR22mkII
Behringer Uphoria. This one is a great deal because it has 4 inputs, and Midas preamps are pretty darned good. They're not the top of the line Midas preamps, but Midas does not make junk. It also has fantastic reviews. Were it my money, this is what I'd be looking at. I've recently replaced my Focusrite 18i20 with a Behringer X-Air X18 that has these same preamps, so all of my recent recordings are using similar gear.
Mackie Onyx producer at $119. Personally, I hate Mackie preamps, but that's just my opinion, and you know what they say about opinions...
Roland Rubix 22
At any rate, take a look at these interfaces... Any one of them would do what you need, but the Behringer would probably give you a little room to grow. I should probably mention that it's rare that I use more than 4 inputs at once. Pretty much only when I'm recording drums, or the whole band at once.