Just spend a lot of time on the computer and you'll be typing 60 words per minute in no time! Or like 4 years.
4 gigs is an unnecessary amount of RAM right now. I've got 2 gigs and have yet to see any sort of laggage besides from my video card, but that is not related to RAM. I would not recommend getting 8 gigs for a VERY long time. It's just a waste of money on unneeded power.