You might want to have a look at Bidule, from www.plogue.com. I have used it in precisely the way you describe as a VST host on PC, while I sequenced/recorded on a separate Mac. There is also a Mac version of Bidule, though I haven\'t tried it yet.
Bidule is clean, simple, and amazingly flexible and powerful. Best of all, it\'s free, in its current pre-commercial incarnation.