How to speed up my Mac?

Does anyone have any tips on how to boost my MacBook 2.26GHz Intel Dual-Core 2GB RAM? I am debating on upgrading to 4GB RAM because right now 1.82/2 is used as stated in Activity Monitor. I have already used Mono-lingual and XSlimmer as well as OnyX and un-installed programs I don't use and removed big files from my desktop. Any other tips? Thanks!