yes, it will be enough. But get as much ram as you can. That matter here. Sometime, HDD can cause glitch if you happen to multitask while doing audio and HDD is far slower than RAM. So getting more RAM will make the HDD less used.
Your comment about the Phenom not having L3 cache bothered me so I checked into it. The 620 is actually an Athlon and it does not have L3 cache enabled. However, I found an interesting tease about turning this processor into a Phenom by enabling the L3 cache (depends on generation of CPU).