From what I hear: yes. Everyone I know that uses virtualization in OS X prefers Fusion. But remember, you will get better system performance if you use boot camp instead of a virtual machine.

@b:
I agree; I’ve heard that VMware makes more efficient use of dual core CPU’s, and is thus less of a resource drain. That said, the interface of the last version I used is primitive compared to parallels – Coherence (a feature of parallels) allows pretty much seamless integration of the start menu and window panes into OS X.

I’ve been using parallels lately and it has been a bit buggy, using almost 100% of my CPU (both cores) just to perform a system update, so I’d probably recommend fusion. A good way to integrate it into OS X Leopard is to just use Spaces and set the VM to open full-screen in another space automatically, so you can switch back and forth with just a keystroke.

see also: http://www.fluther.com/disc/13502/which-is-better-vmware-fusion-or-parallels-for-boot-camp-on/

I don’t really know how it would work on a Mac, but some time ago I tried VMWare Server and VirtualBox, on a Ubuntu (Linux) host, and VirtualBox was much better overall experience… very easy to set-up and worked really smooth (actually, I still use it, and I’ve never had any problem with it).

@Zarnold -VMWare Fusion now has a coherence mode they call ‘Unity’, and it’s improved a lot recently…

Certainly gets my vote.