My question is...

I want to make a blog, a business blog that is. And i want it to be pretty good on the search engines...

Would i be better to use a website like blogger, or would i be better to install wordpress or similar?

I a guessing that google and the others crawl blogger/blogspot, so if i did, say a Engineering Blog, would it get higher search engine presence than if i did a Engineering blog on a new domain name, not containing the word engineer?

I have search google for some terms, and noticed that forums seem to get good results. I tried this by making a post with a term, then googles the term, and the forum was number 2???

Confused, help =)

Probably best to set up the blog on your own domain -

www.domain.com/blog/

But it's progress on the SEs will depend much more on the content and frequency / regularity of updating than it will on the nature of the set up.

Being on your site, it will benefit from the site's established reputation - both in SEO, and in readers eyes.

Content on your own domain has to be better I think.

However, it is then down to you to make sure you keep all the software packages up to date to avoid security flaws.