I can't use it since it's incompatible with NOD32.
I'm fine with Ava Find and Copernic Desktop Search though. The first one allows me to instantly search for any file on my drive by name; the latter indexes all my documents, emails etc, so that I can search for content within them. Excellent combination.
I'm waiting to see how the MSN Desktop Search will be. It's scheduled for a December beta release.
I don't even notice it's running. Only time you do notice any slowdown is the first few minutes you have it installed and it has to index a lot at once. I wonder when updates are going to come ... or are the updates streamed in? Oh well ...