My Mac Pro is now more than 3.5 years old, and is starting to show signs of age. Still, she is running strong, and her processor and memory combination is still faster than any MacBook or iMac except for the most recent 27" quad-core iMac. Also, I've replaced application and swap drives with SSDs, which pretty much makes any computer scream, and have 8 TB of local storage in addition to boot and swap drives. Looking back, the $5K purchase has been well worth the money.
My Mac Pro, from September of 2006 (3.0 Ghz version) [source: primate labs blog](http://www.primatelabs.ca/blog/mac-benchmarks/)
The graph above is a wake up call, though. Should I be sitting around waiting for renders? I'm sure a new Mac Pro would absolutely fly through them. The top entry in the graph is an 8-core Mac Pro from early 2009. I'd certainly like a home machine with a faster memory bus and compatibility with newer, faster video cards, but I am going to wait until there is a big jump in architecture or design; the old machine from 2006 is still going strong.