What do I need to Upgrade to play high end PC games?

I was just woundering what I need to upgrade in my desktop to play better games with no lag such as Far Cry3 Skyrim minecraft with X512 texturepack and mods saints row 3 & 4 etc…

These are my specs in my computer right now

Processor: Intel(R) Core(TM)2 Quad Cpu Q6600 @2.40ghz
installed memory: 8.00 GB
System Type: 64-Bit operating system/Windows 7
Motherboard type: DDR2
Graphics Card: NVIDIA Quadro FX 1700

on a side note I meet the requirements for skyrim but still lag
on all low settings same with saints row 3

The graphics card. Quadros are workstation cards. They are absolutely worthless for gaming. You need a regular GeForce card, like the GTX 750 Ti or something at least.

SKYRIM wants:
-DirectX 9.0c compatible NVIDIA or AMD ATI video card with 1GB of RAM: Nvidia GeForce GTX 260 or higher; ATI Radeon HD 4890 or higher

You may try stopping all background running programs:
Like e-mail searches, upgrade searches, security scans, Defragging, et cetera.

Definitely the graphics card, and maybe the CPu and mobo. Ddr3 is better than 2

PC gaming requires very little processing power. These games are coded to use your GPU and not your CPU. A GPU upgrade would make a big difference for your. I would consider a new CPU and board in a couple of years. I would aim for a GPU in the 175 to 250 range, depending on your requirements and expectations as a gamer. More would yield better results, obviously.