Hasta La Motion!

I know that this topic has been discussed so many times but I could not something on the net that would settle my mind down.

My first choice:
Dell PowerEdge 6650 4 x Xeon 2.80 Ghz/16 GB DDR SDRAM 2x36GB SCSI RAID 2 *1000 LAN

My second choice:
IBM E-server Xseries 365 4 X procesoare Xeon 3000Mhz 8094Mb Ram, 109.2GB HDD, DVD Drive, FDD, NIC DualEthn, 4 x Num of CPU’s, 3 x O/B ethernet, SCSI Card, 3 x SCSI HD 36.4, 3 x USB Port, Rack, Black, W1

My third choice:
HP Proliant DL 580 G3 Xeon 4 X 3.0 Ghz/ 6GB DDR2 ECC/ 4 x 72 GB SCSI Raid/cd / Rack / Lan 10/1000

My fourth choice:
Hewlett Packard Workstation xw8400 – 2 X Xeon Dual Core 5160 – 3 GHz, SATA (Raid) RAID 0, RAID 1, RAID 5, RAID 10 – 4 GB Ram, 250 Gb HDD, Combo( DVD&CD-RW) drive, FDD, 10/100/1000 ethernet, SoundOnBoard, 8 x USB Port, 2 X Placa video profesionala Nvidia Qudro nvs285

I know that these are primarily designed to work as a server!!

My question is which will better run (or run at all!) any Autodesk software such as FFF.

Can you advise me on one of these choices or something else. The price difference among the above models are negligible.

Thank you in advance.