It’s really up to you, but I prefer hyphens. They are nicer to read, and I believe they help with SEO, too, as the words can then be distinguished. Mixing caps and lower case is also a recipe for typos, too.
[font=verdana]They can make it easier for search bots to distinguish the different words. While Google can pick out individual words from a stringofwordswithnospaces, there’s obviously a bigger risk of it getting ot wrong than a string-of-words-with-hyphens. It’s also much easier for other people to type in and to read, which has an impact too.
In terms of casing – unless there’s a particular need otherwise, it’s always a good idea to make sure your server is not case sensitive. You can then promote website.com/URLinCamelCase to make the words more obvious, but if someone types in website.com/urlincamelcase, you want the server to give them the right page and not spit back an error.[/font]