According to the statistics, you're averaging about 5.5 points per WU. That tells me one of two things - 1) you have systems that are very unstable and are turning in a whole lot of incomplete WUs for very little points or 2) you've been a frequent victim of misreporting of WUs (I once turned in about 350 WUs in one day according to Stanford - the actual number was 2). Most likely it's the latter.
Pretty much the number of WUs is meaningless due to the inability of the servers to, well, count accurately. Take a look at your stats here
. It shows 9600 points on 8900 WUs in October and 404 points on 48 WUs on the 17th, both of which are not realistic unless your folding farm is horribly unstable or you're having problems reporting WUs.
What you need to do is check the log files on each of your folding machines. Most likely you'll notice lots of reporting errors, but if you see lots of early unit ends, you'll need to tweak your OC settings to get your systems stable.
Even on a farm that has an accurate WU count, WU count isn't all that relevant since they vary greatly in the level of effort needed to complete them. As was stated above, you'll move through the ranks much more slowly the higher you get (barring having an insane amount of your computers at your disposal as Ronin did). You moved up four ranks this week, which is not at all bad in the top 100. If you think that's slow, wait until you get up in the top 50 or 20! I think I sat at 17th for about three months before moving up at all.
Just keep turning out the work, and you'll make your way up the leaderboard all the while contributing to a great cause.