Best Url Structure?

When trying to rank for a keyword, is it better to form your url like this:

Keyword.mywebsite

Or like this:

mywebsite/keyword

I'm assuming that google weights both urls the same, but decided to ask just in case

I find mywebsite/keyword, combined with good title tags, more effective.

mywebsite/keyword because you're getting authority from your domain.

Thanks for the quick replys

You bet.

Yes, its the difference between "sub domains" (keyword in the front) as opposed to "sub folders" (keyword in the back). Google supposedly treats sub domains as far as ranking purposes go, as separate websites. I think there is some connection, but the word is that they won't carry link juice from the main domain to the sub domains.

With sub folders you get full authority and link juice from your domain to the sub folder pages... if that makes sense.