My preference used to be to work in different projects then consolidate in a m,aster project. Oddly enough I use Media Studio Pro and version 8 now supports multiple timelines. So I can have the complex bits in different timelines and consolidate in a master timeline all in the same project.
But hey its probably a case of what works for you!
COMPAQ something or other with 500Gb Boot Disk, 1Tb external Firewire Disk, 4Gb Memory and a super duper sound card, 19" TFT Monitor etc etc etc
Sony TRV33e : Sony TRV310e : Canon XM2
Sony Vegas Studio editions to v11
Remember, there is always more to learn than there is to teach.