You should be able to OC your CPU and not the RAM (motherboard permitting). If you have never overclocked before, you need to read and read. While OC is very easy and usually safe, you can damage parts if you are reckless and unprepared. You will need an aftermarket cooler if you don't have one.
When overclocking a Core2, unlink the RAM and FSB. Then you will increase FSB a little, stress test. Repeat the process until a higher stable clock is achieved. http://www.tomshardware.com/forum/259899-29-core-overclocking-guide