I'm pretty sure that for anything other that working with photos/videos/animation, the MBP can handle having VMware and OS X running.
I haven't noticed a dip in my day to day activities.
Also, something I just noticed is that Quicksilver recognizes programs in your VMware (at least with Boot Camp partitioned). I can launch Office 2007 through Unity nearly instantly with Quicksilver. If only I could automatically open docs through Office 2007 that are on my OS X desktop...