No problem with taking it to 5GB.
Your machine is:
Apple MacBook "Core 2 Duo" 2.13 13" (White-09) Specs
Identifiers: Mid-2009 - MC240LL/A - MacBook5,2 - A1181 - 2330
RAM Type: PC2-6400 DDR2 Min. RAM Speed: 800 MHz
Details: Supports 800 MHz PC2-6400 DDR2 SDRAM.
Standard RAM: 2 GB Maximum RAM: 6 GB*
Details: 2 GB of RAM is installed as two 1 GB modules, no slots free.
*Apple officially supports a maximum of 4 GB of RAM but third-parties have been able to upgrade the system to 6 GB of RAM using one 2 GB and one 4 GB memory module.