What's the word on upgrading from Parallels 3 to Parallels 4? Is it a solid upgrade? I've used Parallales 3 for the past year with good success -- it has its issues but has been largely stable since the revisions earlier this year. And Parallels 4 seems like it would run faster on my C2D MBP and the multi-monitor features would be a step up. I've seen some of the negative reports on the Parallels forum, but every software release has some problems. Do these seem isolated, or the norm? Thanks!