funny_polymath
Fractal Fanatic
Why can't you continue to use Garageband?
Firewire 800 is the fastest I/O right now, but I don't think any of the audio interfaces actually take advantage of it unless you want to end up spending a good bit of cash.
I would also hold off as I heard the industry is going to be hopping on the Thunderbolt bandwagon shortly.
You can record more than 8 tracks on Garageband. What do you intend to do with the recordings?
Actually, firewire interfaces in general are neither the fastest, nor the most reliable. Depends on how much audio and/or midi you're shipping around.
I use an RME DigiFace with Apogee Rosetta as my interface. Never, ever burps, gets overloaded, drops a sample frame.
My DAW is Samplitude - a virtual unknown here in the States, very popular in Europe (the massive Vienna Symphony sample set was recorded and mastered with it). Their support is so-so. The software has often been years ahead in some areas. Right now, Samplitude Suite comes with so many plug-ins, synths, drum kits/programmers, and a high-end sampler (not to mention amazing noise removal and convolution reverb) - and an analog plug-in suite for mastering, a pretty damn good Guitar modeler that I'd heartily recommend IF you didn't already have the Axe - I mean, this thing is LOADED with features, for tracking, mixing, mastering, burning - all in one program.
But it ain't cheap.
The REAL issue with DAWs is not just features - it's mindset - Logic and Live and Pro-Tools and Samplitude all reflect different ways of thinking about the tasks at hand. Some people find Samp excessively 'widgety' - certainly the interface can be busy (adjusting with skins, docking, closing un-needed windows etc. can ameliorate the newbie-intimidating profusion-confusion) - but like Photoshop or After Effects, Samp is VERY VERY deep. Super damn deep. And with power comes complexity. I still sometimes record something in Live, 'cause it's fast and 'fun', though their reverb etc. are a joke compared to Samps (the Axe's verbs can't stand up to samps either, IMHO, but they are two different animals). But for serious projects, it's hard to beat the big boys. For me - I never liked how Pro Tools used to lock you into THEIR hardware. I never liked Logic's 'left brain' orientation (admittedly, I haven't looked at it in years). Samp is also left brain compared with something like Live, but for me it works.
I'd looks at tutorials etc. before you buy - get a feel for the different feature sets, but ESPECIALLY for the different work flow and User Interface philosophies. There is no one 'best' DAW; there is only what's best for YOU.
Best of luck.