Honestly at this point, there is so much to take advantage of in the .Net 4 (vb) language and the paradigm shift is so significant, that I can't imagine taking my older VB 6 projects and trying some sort of straight conversion. The conclusion can only be some sort of raw kludge that you'll end up redesigning anyway.
Most of my VB6 projects are 1/2 the lines of code in .Net upgrades. Plus, there are third party tools (DevExpress / Telerik come to mind) which can take any stuff that used to take you 100+ hours to develop in VB 6 and make it a few line piece of cake.
Unless you're simply extremely strapped for time, take the plunge - you won't be sorry.