As a former PolySix owner and fan also, it's worth noting that Korg has already announced a softysnth PolySix is coming (originally it was supposed to ship 3rd Quarter of 2003 but I suspect it'll be released at the upcoming NAMM show).

I've been using Reason for quite a while with my laptop and I love it - it's not as CPU intensive as some VSTi's and is more of a complete studio rather than just a single instrument emulation. But I think we're seeing a revolution in the making with softsynths - several of us in another forum have a bet going as to which we'll see more of at NAMM: hard or soft synths?

Several midi controllers now also contain an audio interface built-in and I look for a lot more to come out at NAMM. This would be the ideal thing to use with a laptop so you might want to wait and see what comes out later this month.