Controlling the Search Process
The following table documents some common attributes that you might or might not want. Each is discussed in turn after the table. Note that if a feature is available, but buried so far inside the product that effort is required to find it (can you use a search tool to search itself?), then that feature is written off as missing.
Specifying Index Location
Here's an idiotic thing: Most search engines won't let you put their index file (their keyword database) where you want it. It would be ideal to put that file in a separate disk or in some less-critical spot where backups won't catch it, but that's generally not easy. The tools that do offer this feature, Yahoo! and AutoFocus, are way in front.
Windows 2000+ lets programs scan the disk even when other programs are busy updating files (file locking). This lets search engines do their scanning quietly in the background. You want this feature if you can't leave the computer running overnight, or if you can't afford to have the scanning process bringing the computer to its knees. Unsurprisingly, all the products do it, with AutoFocus needing just a bit of a nudge.
Legacy Index by Scanning
As a last resort, the tool should be able to go back to brute-force scanning of the disk. That's important for non-Windows 2000+ desktops.
Engine Download Size/Install Size
Some of these tools are tiny; others are massive. Experiment with Google or Ask Jeeves if you're on a dial-up Internet connection.
After you install (and before scanning is started), the tightly packed downloads mushroom up to more realistic sizes.
Combined Local/Remote Search
This convenient feature blurs the distinction between online resources such as web pages and what you have on your disk. Where the feature is available, you can search everything at once, where "everything" is defined as your files plus all files publicly available on the web. By itself, harmless and possibly useful; combined with the next item, it's a political agenda.
It's one thing for a dumb search engine to grope through all your private files. It's another thing entirely if that search engine starts connecting to other applications and to other people's computers while it's doing so. Privacy issues might weigh on you heavily.
Disturbingly, several of these search engines talk to someone else while they're examining your crown jewels. Google sends an identifier back to the main Google server. ("It's anonymous!" protests Google Public Relations.) The MSN Toolbar Suite has a relationship with the MSN web site that's unclear at best, and both the MSN Toolbar Suite and AutoFocus poke around inside your email system, which could easily result in them delving into an organization's email server infrastructure.
This sanity feature lets you restrict the set of folders or directories that the tool will index. Indexing c:\Windows is probably a waste of time, and you should be able to stop that.
Indexing Progress Indicator
While the engine scans your files, possibly for hours, it would be nice to get some feedback that indicates how it's progressing.
Some tools tout their ability to recover from a corrupt or damaged index. If you have a disk error that corrupts the search engine's database, it would be nice if a) the tool didn't fall in a screaming heap; and b) the tool didn't need to rebuild the whole database from the beginning.
File Type Filtering
Another sanity option: Tell the search tool not to scan your DVD or MP3 collection or your digitized photo albums. You should be able to exclude specific file types from the search.
Does the search engine provide a cute search field on the Windows Taskbar?
Support for Compressed Files
Documentation is sketchy on this point, but it would be helpful if a given engine could look inside a .zip, .cab, .tar, or self-extracting .exe file and examine the other files inside it.
Support for Legacy File Formats
There are billions of crusty old file formats out there, from FoxPro to Access. Some search tools take pride in understanding them all.
Ignoring Network Drives
You probably don't want the search engine indexing drive H:, especially if that drive happens to be network-mapped to a file server holding millions of files. Note that enterprise versions of some tools (Google and AutoFocus, for example) provide alternate systems for doing just that.
Click To Suspend
If you get fed up with the slow indexing and scanning process, it would be great if you could temporarily halt it so that you can get on with other trivial matters, like earning a living.
Click To Exit
It's my computer; I want to be able to shut down the search engine easily. The MSN Toolbar Suite is a little odd in this respect. Shutting down isn't difficult, but if you use the Classic desktop design under Windows XP, you'll have to do a bit of hide-and-seek if you want to start the search engine again.