Ah man, good post. Well let me give you my experince.
I Started with a 4track cassette (2 actuallY) then to a Roland vs840EX (8 trk digial), which upped my sound quite a bit. Then i upgraded from there to Cubase (SE $99.00) on a $300 refurbrised E-machine's 900 mhz computer using a audiophile (m audio) 2496 sound card, and thats when my sound turned pro. That gave my about 20 tracks without straining the system (cpu) as well. I like porta studio's for the portabilaty. But Inputs and Preamps were a big let down (compared to my m-audio card). With the Porta studio's you are stuck with what you got. With software you can always upgrade. There's allways new tech that you can easily add to your set up. Sell a old card, program, ect. and buy a new one. That "open endedness" (?) makes software a better choice period. I upgraded my pc to a 2.6 ghz (Refurb. E-machine ) for only $329. See
www.tigerdirect.com. Now i can do 48 tracks easily (never had to).
But you will most definatly need a dedacated space for your setup (PC). With portastudio you can go to ya boy house who's on house arrest and drop his vocal (for instance). Or if your group working on a project and your girl/wife/mom be tripping 'bout all the company, again PORTASTUDIO.
I'm pretty sure portasudio's have gotten much better since mine (inputs and all). But its really more to consider than just sound quality. Sound Quality should be very comparable. Its "how you use it" now a days not just "what you got"anyway.
**The negative side of software (PC/Mac) is compatability issues. They can make you wanna throw everthing out the second floor window. Be informed before you buy*******
****But another plus is you can do everything one it. Production, CD Labels, Websites, ECT********************************
Hope that helps/ TAK