yea using lr2 and raw files is gonna eat your memory fast. i upgraded my ram when i started using lr2. i personally shoot raw+jpg incase i get lazy and dont want to edit as much. with raw you can do a lot more changes than with a jpg file. fixing a wb issue is so much easier in raw. i could go on and on about it but you seem to have the basic knowledge of what it can do. if all your work has been jpg id love to know what youd do with raw files.
quick google
http://digital-photography-school.com/raw-vs-jpeg