Yeah if you aren't worried too much about money..I'd go for a new build. It's always great to start new(unless it's not worth it).
BUt I've looked at ur motherboard..and here are the best parts ur current mobo can support.http://www.amazon.com/AMD-Phenom-Processor-Edition-HDT90ZFBGRBOX/dp/B003FVI2KQ
I'd say get one 690..but that's really expensive..tbh one 680 can get the job done.http://www.newegg.ca/Product/Product.aspx?Item=N82E16820145345
(get two of these max 16gb).
Are you comfortable upgrading the mobo? Give budget if you are
Unfortunately I can't find any online distributer of that processor. So try a local shop or some other site :S.