You would do much better with a new pc, that workstation is Old. Almost any Xeon cpu from the 1155 socket or 1150 socket, are on the same level as the Intel Xeon Quad X5647@2.93Ghz, in some cases the new cpus are better.
Why should you Build your own pc?
First of all you get to choose Quality Hardware components, that will last alot more than the prebuild workstations from dell,lenovo,etc.
Second, you get no restrictions if you want to upgrade later, you get to add more ram next year, add more hard drives, add another gpu, etc.
Third, When its time to upgrade again in 3 or 4 years, you will already have the Case, psu, HDDS, and Maybe Ram to Reuse and will let you to get even better Top of the Line Hardware.