…and to drive the point home:
Cinebench 9.5
My old 920 cpu: 2855 points.
2006 mac pro: 1437 points.
The new mac mini would leave the 2006 mac in the dust as well with more modern cpu’s than mine.
Ref:
All I hate about this computer is no screen, no nice GPU, and the RAM is pricy
I see your point, but how much did you pay. Plus the mac mini maxes out at 8gb of ram, i might need 16. With the mac pro i can put 4tb of storage. Plus its quad core with 2.66 ghz each, and i can overclock to atleast 3 ghz
A Swedish computer magazine did a test like a year back running Windows 7 on a whole lot of different machines - including a MacPro and a MacBook Pro. The Mac’s were the fastest computers in the test though not being the highest spec’d. And don’t ask me why, hehe, and the testers were also as surprised as anyone…
I must agree with Herbert above, you’ll need to upgrade RAM & GPU and that will be pricy. You’re probably better off buying an used iMac 24", even with the 8Gb RAM barrier… 
The price I paid is not important - you will get better performance than mine with the mac mini i7, at a price you can afford.
And there are vendors that offer a 16gb upgrade for the mini:
And overclocking on a Mac? Mac Pros always have had slight heating issues, so even if you would use zdnet’s overclocking tool, it would probably be a bad idea in the long run. Don’t know, I know of no mac owner who will run the risk of losing their warranty. Even if you do overclock this machine, it will not be able to compete with a modern i7 or i5.
Storage is not a problem - you can add even more hard drive space through Thunderbolt.
However, did you check which video card is installed in that macpro system?
Honestly, I think this machine is a classic case of a ‘money pit’. Getting a second hand iMac, as Farmfield stated, may also be a better idea.
Need to back up what Herbert posted. Steer clear of the Core 2 era Mac Pros, they are not worth the cost, especially the older ones (the 2008 model will still be able to run Mountian Lion, I believe, can use some newer graphics cards, and uses 800Mhz RAM).
Also, remember that CPUs have gotten faster clock-for-clock in the last few years. So “4 cores 2.66Ghz” might sound comparable to the Xeon W3530 in the current Mac Pro, it isn’t. It will probably have only 50-70% of the performance, mostly due to the comparatively awful memory bandwidth and lack of hyper threading. (also, said Xeon W3530 is itself a very old part, basically an i7 930 with ECC enabled, and due to be replaced with the new Sandy Bridge Xeons imminently).
A new Mac Mini or a lower-end iMac is a better choice. An i7-era Mac Pro might be decent, but I’m not sure they can be found for less than $1k yet.
I’m running one of these 2006 Mac Pros (Mac Pro 1,1) at my dayjob. It’s not a 3D box, but I’ve definitely used Blender on it a bunch.
I have 5gb of Ram and whatever graphics card came installed. I’m sure there are lots of cheap PCs that have more muscle for 3D graphics…
It’s a good computer though. Rock solid. easy to upgrade. Not sure if you’ve ever had a Mac Pro, but they are fucking HUGE. They take up a lot of space.
I agree with most you’re saying but I also feel the need to point out that we’ve broken Moores law for a while now, the latest CPU’s aren’t as fast as we think. I run a 4 core 1st generation [email protected]… A new 3rd gen i7 with 6 cores running at 3.2Ghz is about 15-20% faster… So it’s not faster per core than my old i7… But then memory & all that is faster, but that’s marginal…
So what I wanted to say with this wining was, the 2x2.66Ghz Xeon’s in that can isn’t very slow either… 
BUT… In regard to costs for RAM and upgrading the graphics card, I’m not sure anymore… If you want to keep a box for 2-3 years, perhaps even 4 - by then it’s a 10 year old machine. That’s, well, ancient. 
I have decided Im gonna buy a 999$ 2011 imac. It seems a lot cheaper