Is upgrading from Mac Pro 1,1 to 4,1 worth it?

I use my 1,1 for music production and it's starting to chug...(imagine that after 7 years)...Anyway, there's a 4,1 for $799...

So -
2.66 Xeon Dual core vs. 2.66 Nahelem Quad Core

1,1 has 5 gb ram 4,1 4 gb ram

Would I see performance improvements? Worth upgrading?