go for the normal RAM, no need to throw money at ECC, unless your doing somethings that are extremely, extremely, mission critical. The idea was that back in the day, ECC RAM would lock the computer up if it detected an error, say a bit changed around. It's a nice idea for banks and such, as I'd have to have my 9 turn into a zero.. But, RAM has gotten so much more reliable, and I run servers. Both dual processor and single, and have never used ECC. No problems that I know of!
-Phil