If you plan to upgrade, an Lga775 has definite drawbacks. All memory accesses go through the Fsb bottleneck, meaning that a quad-core won't be efficient. And then, nothing new goes on this socket.
Amd in contrast keeps socket compatibility over large time spans, and as games often make use of quad-cores, you will probably want to have one.
Very different from my situation, where all applications (except 7zip!) are single-task, so I chose a dual-core because single-cores didn't keep up and took the E8600 because it's the fastest on single tasks and draws less power.
Take from the beginning a good mobo, with huge expansion capability (at least one x4 Pci-E and many x1) as the mobo is the part one keeps longest. Remember you'll need Sata600 and Usb3 and 10Gb/s Ethernet soon, and no chipset has it integrated, so everything will need fast expansion ports.