What is your url? Having that many links doesn't mean jack if many of those sites don't have a decent PR.
It's also important the quality of pages that links to you. In some case bad quality links can even decrease your PR.
Just out of curiosity, and it may be another answer to your question, how did you get that many links so fast???
Because most of those links won't carry a lot of PR juice to you, meaning a lot of those links won't have a lot of PR juice themselves. PR5 is good, I'd be happy with it.
no wonder u have 300k pages indexed... http://www.fileplaza.com/popularsearchphrases/a.html If I had a site like that I wouldn't ask around why I have pr5 and draw any kind of attention to my site Google loves that kind of spam..
Wrong. Google recently put more emphasis on link relevancy then quantity of links. Getting links from high PR sites doesn't really matter more.
The quality of links means a lot. Basically instead of looking at the quantity of links look at the total link value the link value = [Linking Page's PageRank] / [# of links on Linking Page]
Backlinks are great but they are not proportional to PR. If you have lots of splogs linking to you, that might be why too.