I've recently changed my web host and it seems the new one allows sub-domains; ie. shop.mywebpage.com, information.mywebpage.com...

My question is, does a relevant sub-domain name help in SEO? My domain name is unfortunately not the same as the keyword I am optimizing for, though I have a PR of 5 and am on page 1 (10th) of Google when searching for the relevant keyword - we have quite a lot of relevant backlinks fortunately which has helped in ranking in Google.

I am thinking of creating a sub-domain like relevantkeyword.mydomain.com with the hope that this will raise my rankings even further with Google? Does anyone have experience with sub-domains? I have the feeling that relevantkeyword.mydomain.com will get given a PR of 0 after Google's next major update, rather than automatically get assigned a PR of 5 with the main domain.

Any comments anyone?