Having seen the Tiger demos, I was really impressed by Spotlight and Automator. On my PC, I shelled out 70 bucks for X1 search and all it does is make my system hang (actually just removed the damn thing) so the promise of built-in real-time indexed search combined with the Photoshop Actions-type Automator feature was enough to make me give the Mac another shot. Yet another disappointment!
Spotlight doesn't even support boolean search. You can't specify words to exclude or phrases, etc. For mail, you can't specify that only the subject should be searched, the body, specific date ranges, etc.
Automator? Only supported by the current system apps that come with the OS. It'll be a year at least before the major applications integrate it into the latest versions of their software.
Final verdict: One to watch but not terribly useful today. I'll take a look again in a year. Kitten definitely has promise but it has to grow up first.
The Tiger? More like Kitten! article by Aral Balkan, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial 2.0 UK: England License.

For your PC you should check out Copernic Desktop Search, been please with it so far. Only thing to watch out for is the boolean/wildcard searchs, as it doesnt support those yet.
Seems like you might have missed some of the power user features in Spotlight, as explained in this post at the mac geekery blog…
http://www.macgeekery.com/tips/how_to_execute_raw_spotlight_queries_in_the_finder
Maybe this kitten can really purr!
Speaking of search programs for your PC, I just tried installing MSN Desktop Search (http://www.imagine-msn.com/search/tour/desktop.aspx), and I’m really, really pleased with it. The “search-while-you-type” function is great, and it has a lot of options for searching only specific file types, for example, or only email subjects etc. Check it out.
@Bill: (kMDItemKind == “*PDF*”) && (kMDItemEncodingApplications != ‘*Windows*’) … I’m constantly amazed by how easy the Mac is to use ;) Seriously, though, thanks for the link. I knew it had to be possible at some low-level. Hopefully, they’ll expose this through a usable UI in a future upgrade.
@Ryan & madsb: Thanks for the suggestions. I’m pretty sure that MSM Desktop Search will not search my Thunderbird email. I just had a quick look at Copernic and it appears to… downloading it now!