Upgrading may not be an option for OP. To answer your question, the OS cannot be loaded onto the SD card. Memory can be an issue with the Mogul/Titan/6800. You may be having a problem with an accumulation of junk files (internet debris, etc). A clean up app will help clean this up. MemMaid (
www.dinarsoft.com) and SKTools (
www.s-k-tools.com) are popular around these parts. Also, install as many apps as possible to your SD card, except for those that run on start up.