i'm a cubase man myself, it took some hitting my head against a wall to figure some things out, but it's solid, i'm still on sx 2. in the past i've used both fruity loops (cheap) and KRISTAL (free) and found them both effective, and good for my wallet.
http://www.kreatives.org/kristal/index.phpa good link that lists more options is:
http://www.hitsquad.com/smm/cat/MULTITRACK_RECORDING/for computer hardware i'd recommend something over 1 ghz with 512 ram to generalize, but 2 ghz and up would be better, your alesis, which i don't have experience with, but looking at the descriptions, should do a fine job unless you're having problems with it? is it the firewire or usb variety? i prefer an interface with firewire over usb, i've heard and seen too many problems with usb interfaces to rely on them. but i'm sure they work fine for many people. if you sold it you'd either have to use the basic soundcard input on your computer, which i don't really recommend, i mean, it will do the job, hell, i've used it for years, but there's no assurances for sound quality. or buy a new interface, which completely defeats the purpose, if you are selling your current one to fund some pedalage. i use a firepod and it's worked great for me. almost every interface i've researched has had some amount of people screaming about what a giant piece of shite it is. which leads me to believe that either audio interfaces are notoriously shoddy, or that people, no matter what their computer experience have a universally difficult time setting them up right.
but ultimately, in my opinion, gear is gear, you get what you put into it. you could plug your guitar straight into your computer and create masterpieces, as long as you know what you want and understand the equipments limitations.
and if i've been condescending, or stated the obvious, no disrespect was intended, just attempting to cover things, not knowing your experience. hmmm, and i ramble, sorry about that.