well, the apogee duet is a high quality interface, though yes its kinda limited, but its well known for having good ADC and DAC's. the inspire has fairly decent mic pres on it, so should be cool for what you want it to do too though, if you're just using two mic pres. my friend who sings in my band has a presonus firebox, seems very similar to the inspire, but it has more line in/outs. that runs nice and solid and is fairly good quality. im currently using a motu 828mkii, because i need a fair amount of IO (playing live we use about 8 discrete outputs and 4 or so discrete inputs).

i have been using cubase since i started recording and i started off using cubase sx, then got sx2, then sx3 now on cubase 4, and with the release of cubase 5 just round the corner with some tasty features, i might upgrade to that too.. i used cubase LE when i first got my macbook in the period while i was waiting for cubase 4 to be delivered, it was okay but felt a bit dated and cut down after using sx3, but it depends what you want to do with it.

the guy with the presonus firebox uses cubase sx3 on his pc laptop (cracked) but has cubase essentials 4 installed on his macbook, it seems a fairly decent version of cubase considering the pricing difference, its about £40 i think.. compared to around £400 for cubase 4.. all depends what you want to do with it (like cubase 4 has extensive monitoring facilities and offline processing, more inserts/sends and stuff like that) but if you are just laying down simple tracks you should be ok with either cubase LE or if you find it a bit limiting, then try out cubase essential 4 maybe?

you could always look into using reaper too... its pretty damn good, and can be used for free. quite similar to cubase if you're used to that already, but theres some differences though only small.