.. I did read somewhere that you only need RAM if your page outs are higher than your page ins and that if it doesn't, you literally won't notice the upgrade in RAM in terms of speed quality.
What really matters is the amount of pageouts that are actually occurring. The pageout number is cumulative and shows only past activity.
Running Lion with only 2 GB is almost certainly going to be slow. Buy more memory. More is better. Purchase Mac memory from either OWC / MacSales or Crucial. There are other reliable vendors but those are the only two I have used personally and can recommend.