Easy, get as many apps off the phone’s internal memory as possible and move them to the SD card (done from the application menu under Settings.

Other than than, no real way to do what you want, without overclocking the CPU, and you can NOT do that without rooting the phone, and then flashing an over clock-able kernel. Easy to do for some people that can follow directions, and not others. So if you feel this is something you want to do, check out the XDA forums for your phone.

ÿou can start here, with these threads:
These two links say they are easy versions

http://www.youwantthat.com/?p=411

http://www.techlivez.com/forums/android/

These two links are more indepth:

http://forum.xda-developers.com/showthre

http://www.xda-developers.com/tag/samsun