This is what I posted about my experience in another thread:
I've been jealous of my friends mac's and the cool VMWare Fusion seamless integration for the past year or so.
I also stopped pretty much all use of *nix environments about 6 months ago when I switched jobs from a system administration position to at a unix heavy company to a developer position at a microsoft heavy company.
So I decided in preparation for my Masters courses I have coming this fall in computer security and for the sake of retaining all that which I have learned, it was time for me to immerse myself in Linux as much as I can (which unfortunately is not possible at work), but I can get my home desktop and laptop. The latest release of Ubuntu 9.04 was a great opportunity for that.
I jumped in and installed it on my desktop. Very quick and easy install. Automatically detected my wireless USB and all wireless networks in range. Immediately the nvidia drivers popup notified me to install the drivers for all the eye candy. 1 minute of downloading later followed by a 24 second reboot and I was in full dual monitor bliss with all the compiz/cube eye candy I could muster.
I then installed the following, ubuntu-restricted-extras, gnome do, ubuntu tweak, compizconfig settings manager, dropbox, samba/sharing. Then I stumbled across an article that talked about Virtualbox's ability for SEAMLESS INTEGRATION, just like VMWare Fusion. I had no idea they had this going on. Last time I used virtualbox was years ago and I was less than impressed. I decided to install virtualbox and Windows XP. About 15 minutes later it was all up and running and I am still in shock at how awesome this is. It just WORKS. I have microsoft office and the other few windows only apps installed on there and it just is seamless right on top of my ubuntu, fully integrated. There are a few hiccups now and then where windows and ubuntu seem to engage in taskbar wars, but it's nothing major.
I also found what really seems to work for me is to simply maximize the windows machine on a separate cube desktop. It automatically switches resolution on the fly to match how the window is. Running Remote Desktop inside the virtualbox is just as fast as running it beforehand.
Also, I immediately performed the same setup on my laptop after it all worked so well on my desktop. I simply exported my Windows XP virtualbox config, copied it over to my laptop, imported it, and it worked flawlessly. I didn't expect it to work as well and easy as vmware, but it worked great.
All in all it works wonderfully and looks absolutely beautiful. I am very impressed and very pleased with this setup and I don't see myself installing windows as a host anytime soon.