Why VMware will win
VMware will win in the long run. All the little features that Parallels keeps adding, are ALL on the VMware roadmap, VMware is just a bigger company that has high standards for quality control. I've been lucky enough to visit VMware and see their betas (the ones not released) and the user interfaces, and feature set make Parallels look bad.
Did you know that Parallels isn't even a true Cocoa application? it's a qt app, that has JAVA for it's interface! Fusion on the other hand was built from scratch, from the ground up with x-code, and is a full-blown cocoa application. Most of the team at VMware are ex-apple employees, as well as their user interface designers. While Parallels make look sexy, and have more functionality now it won't be able to hide its true colors for long.
Take the latest Parallels beta, with "usb 2.0" support. It's absolutely crap, you can finally see they are building on a "house of cards". I do admire the Parallels team, they were the first out, and did us all a HUGE favor. But when I plug in USB 2.0 stuff, and my machine HANGS (java libs loading), and kernel panics because of my two USB hubs it starts to get really annoying. Or try installing the Parallel Tools while having a DVD in the drive... You're in for a REAL treat!
Not to mention the way Parallels shares it's resources with Mac OS X. For example, I have a Motorola Q phone, which recently had a fantastic software update, that of course was Windows only. Being that Mac OS X, DOES SEE the Motorola Q, and So does Parallels I fired up the .exe with the hope of Updating my phone firmware through Parallels... Obviously it didn't work, it can't properly share if Mac OS X, "grabs a hold" of the device so to speak.
So I did the exact same thing in Fusion (which is an early beta), and my computer didn't freeze while it loaded the VM, didn't KERNEL panic, and Installed the FIRMWARE UPDATE TO MY PHONE!!!!!!! This is absolutely INCREDIBLE USB support. It's very complex to do a firmware update to your phone (easy to fry it period), let alone work properly through a VM, when Mac OS X is also trying to access the phone at the same time. This to me was impressive! VMware's products (windows & linux) have always had amazing device support, and with the release of the next version of workstation (very soon) ;-) There will be graphic acceleration!
While I do love the features of Parallels, for now I've stopped using it, it's not stable, and craps out anytime I forget to unplug all my USB devices....
It just shows at the heart of Parallels the app IS built on a deck of cards. VMware on the other hand is a object-c Cocoa with rock-solid base, that features can be built upon, and will also be able to use whatever new features, looks, style, resolution independence, and other features offered by Leopard when it ships.
Not to mention the 9,000 + pre-build virtual appliances you can download from VMwares site or use with ANY platform.
Just my two cents...