I need a new PC and dunno which one is better for me.
Intel Xeon 5140 or
Core 2 Duo E6400
I'll use it with a 256 MB nVidia Quadro FX3450 graphic card for 3D modelling (such as Autodesk Inventor) since I'm a mechanical engineer. I probably get one at Dell's. What do you think? Any other suggestions? thx
THe only thing the Xeon will offer you is multi socket support. You will need a more expensive board and most likely FB-Dimm.
If a dual core or a quad core is enough for you, you really do not need a xeon 5XXX. You could also look at the xeon 3040, essentially a e6400 with the Xeon branding(almsot the same price, dunno if Dell offer's them)
Save you money and go the e6XXX route, much cheaper!