The a Dell 435mt is not an ESX Server.
VT-x VT-i VT-d require BIOS /CHIPSET/ PROCESSOR /DRIVER Support.
Having one of the 3 does not guarantee all 3. The 435 desktop is not validated as a Server.
Windows XP, Windows 7, WINDOWS 8 is not ESX Server nor is it Hyper V Server.
Xeon 5400 (DP) or Xeon 3200/3210 (UP)based chipsets have VT-d technology. VT-d requires BIOS support.
Dell Studio XPS 435MT Core i7 1366 Motherboard -R849J. Chipset. Intel X58+ ICH10