It seems they are offering you a "workstation" model, which features the Intel Xeon Processor. This is the "right thing to do" for them, since as a business you will be using these PCs a lot more heavily than the average user.
My company was using several PCs with the Xeon series processor, but we switched to the i9 series and saw a lot of improvement in overall performance in Inventor. In our experience, PCs with the i9 processor are fairly comparable in cost and perform much better with Inventor, even though they are not technically designed for work use.
The spec's they are offering you are very good for an Xeon series processor. However, you will likely see a 15% or more increase in performance with Inventor if you go with the i9-xx900 series of processor (10th, 11th, or 12th gen.). If you ask for this, your supplier might say something along the lines that those processors are less reliable (more on this below). However, I can personally say that I have been using the i9 processor in my workstation for 2 years and have had no issues with it. The only thing you need to make sure of is that you have adequate cooling for the processor and it will last you a long time. My PC has a generic liquid cooling system (these only add $60-150 to the overall cost) and that is sufficient, although I expect even a high quality air cooling system would be enough.
The Xeon series of processors is Intel's workstation line of processors, made for PCs that get used a lot more heavily than your average desktop. The problem is that although these Xeon processors are very capable of doing a lot of heavy work, they are optimized for multi-threaded use. Since most of Inventor's operations are single-threaded, they are not really well suited for Inventor. The big thing about Xeon processors is that you can purchase workstations that have more than one processor. The last I checked you can get an Xeon-based workstation with 80 cores of processing power, which is astoundingly powerful, but completely useless for Inventor.
Intel's i9 series processors run much faster on single threaded operations, which is ideal for Inventor. While they are not classified as a "workstation" processor, they function just as reliably as the Xeon series as long as your PC has adequate cooling. These processors fall more into the "gaming processor" category.
All of the other specs of the PC (memory, GPU, hard drive, etc) seem great!