Not showing up on Google
 

your robots.txt is blocking your entire site from getting cralwed.

Remove the robots.txt file, or enter the proper settings. Here is a good vBulletin Robots.txt file to use.

<font color="slategray">It has been four days since i fixed the robots.txt file, i can see google spiders on my Whos Online board, but none of my threads' content appears on google yet.. I tried searching using the exact title of a thread on my forum and the search returned no results.. Is something wrong here, or does this thing need more time?</font>

It will take a while. It takes 24-48hrs from the time you fixed it for the search bots to get the new version.

Then you can expect up to 1-3 weeks before you start showing in the results

If I don't have a robots.txt everything should be listed, right?

Probably, but it will still take time to be reindexed.

Typically yes, though there are chances and factors that could also mean you dont get listed such as being banned from the search engines for black hat techniques and yada yada

can you tell me what you mean by black hat tech ?

Google it!

Black hat techniques are "optimization" methods that if the search engines find out your using you'll get penalized or removed from the indexes.