From what I've been able to gather the stand-alone boxes just store the data and burn it to CD... with a computer you're just storing the data for a transfer to CD... or to email to the mastering house... or to convert it to MP-3 and post on "MySpace", etc. The stand-alone boxes will require a chassis [just like a computer], a power supply [just like a computer], memory [just like a computer], a read out [screen, just like a computer], audio I/O [just like a computer], a CD drive to burn CD's [just like a computer], and software to run it [just like a computer]... so seeing as the stand-alone things have kinda shitty converters and will need outboard converters [just like a computer] it seems pragmatic to me to just get a computer.
As always, YMMV.