Subdomain relevance

[Steel Dolphin]

[standard newbie disclaimer]
This may be a stupid question but I am a newbie to this arena so please go easy on me :)
[/standard newbie disclaimer]

Lets say I have a site that acts in part as a resource for a specific niche (and is ranked in the neighborhood of lets say 5) but I want to add another semi related niche to this site without starting a whole new domain that is seperate from it but not necessarily completely irrelevant to the content of the main site. would it be in my best interests to do either the following or something else?

create a subdomain for the new new semi related niche like:

keyword.mydoman.com/keyword/keywordphrase.html

or should i just do the following:

mydomain.com/keyword/keywordphrase.html

Sorry for the lack of information here, my thinking is still inthe conceptual stage and specifics are hard to come by :)

thanks for any insight you may be able to give on this.

[jocelyn]

A sub domain is considered as a separate domain. So if you use keyword.domain.xyz then you will need to build links to that site too, because it's a different domain. Linking the main domain with the sub-domain too much is not good.

If you use domain.xyz/keyword then it's part of the same domain and can get links from the main domain without looking like crosslinking.

So it's up to how unrelated the topics are. If you use keyword.domain.xyz, then might as well look for a better domain name instead of the long sud-domain one since it comes up to the same.

[Steel Dolphin]

Thanks jocelyn :)