Launchbar is one of my favorite OS X applications. (Quicksilver is an imitator that is free, and thus gets more attention, but LB came first.) I've long looked for a Windows equivalent. I registered AppRocket and used it for a while, but it was disappointing in the end.
I was surprised then, to learn there are so many XP apps that try to be Launchbar for Windows:
Scott Hanselman's Computer Zen - Replacing Start Run.
Vista has implemented a Launchbar like feature, so maybe others will work to bring Launchbar to XP. It would be most appreciated.
Update: Just noticed one of Scott's update comments: Ctrl-H in Google Desktop?! Wow, that's killer. I much prefer Yahoo Desktop Search to Google Desktop because GD doesn't grok folders, but this might switch me.