Underscores vs. hyphens vs. no spaces

Is there a better choice?

[Soze]

I started my site with pages that use underscores in the urls, but when i searched for key word is was not highlighted in bold. I noticed that google was highlighting hyphenated urls and the urls with no spaces, hyphens, or underscores.

Should I change this before the site gets too big?

[daveVk]

My understanding is that red_widget is treated as one word, that is the underscore is not considered punctuation. Search for prior threads on this subject

[Komodo_Tale]

Lots of computer programming languages have stuff like _MAXINT, which may be different than MAXINT. So if you have a url like word1_word2, Google will only return that page if the user searches for word1_word2 (which almost never happens). If you have a url like word1-word2, that page can be returned for the searches word1, word2, and even “word1 word2″.

[mattcutts.com...]

_

[Bluesplinter]

For some reason, Brett obviously believes differently. He is reorginizing WebmasterWorld with underscores. Check it:

[webmasterworld.com...]

And he made reference previously to someone saying something about the "dash of death" (if I remember correctly). He apparently has his own ideas about it, and they don't seem to match up with what MC said. Shrug.

[phantombookman]

If Brett is using underscores it could be because he likes the look of them. His site is so powerful I doubt a dash or underscore will make any difference to where a page ranks