SEO for my new site

[nodgie]

I'm planning on developing the domain joecybernet.com into a general site where I can put my tutorials & articles (and have several adwords units so I can hopefully make some revenue in exchange for my expertise)

Just wondering before I start which of these approaches is better from an SEO point of view

1) Having all my articles split into sections like
www.joecybernet.com/php/getting_the_date_in_php/

2) or just having no "sections" at all and just have
www.joecybernet.com/getting_the_date_in_php/



or should I put .html after the article name?

Also does using subdomains improve/disprove SEO
eg: php.joecybernet.com linux.joecybernet.com

Any feedback is greatly appreciated!