Welcome to WebmasterWorld, jckos.
There's a little more to creating a good page title than just the colon, but I agree with Damain that they should be able to tell. Looking through SERPs at search engines that highlight search keywords by bolding them should give a first hand view of it.
>add a space before and after the seperator
I do this generally to make certain, though it's probably not necessary and uses up characters, but I use hyphens.
You might want to re-think using the site name at the beginning, unless it has the keywords in it that you're targeting with the page. The page's keywords in the title, that should match up with the context of the body text and be in the major heading, should be somewhere in the first 5 words approximately, the closer to the beginning the better. So you may want to use your best keyword phrase at the beginning of the title with the domain or site name following, preferably in such a way that it has appeal for searchers to click on.
We've had some good page title discussions recently, you might want to do a site search for page title and page titles, and run through a few weeks in the Google forum; we've had several there.
For the main page heading, we'd have to discuss whether it's better to have it long or short, whether it should include only the main keyphrase, and whether or not it's productive to have the site name in it, depending on whether the site name includes keywords.
We could also look at whether it makes a difference whether the keyphrase is at the beginning of the heading.
It's a little more than you asked, but it's a good topic with a lot of details involved that can make a difference in how pages rank.