I am going to buy a HP desktop. I want to install a Q9650 and 8gb of mem. and 750gb to 1tb HD. 8600Gt - 512 mb graphics. I will want to use it for television viewing and surfing, as it will be connected to my big screen television. I want the PC easily upgradable. What do I look for in the motherboard specifications?

What do you need to look for in the motherboard specifications?

I suggest you start by going to HP.com/Support,

http://welcome.hp.com/country/us/en/support.html

In the box to the right of -> product search: <- type your model name and model number.
Example: Pavilion 7955

This will take you to the main page for your computer. See if -> Product Specifications <- is listed.
Click on that. Now see if -> Motherboard Specifications <- is listed. Click on that.

Look to see what processor socket you have, what Northbridge chipset you have, and what the Maximum Total Amount of ram memory is for the motherboard.

1.Processor: Intel Quad Core Q9650
Your motherboard has to have the LGA 775 processor socket. Also know as Socket T.
A.http://en.wikipedia.org/wiki/Socket_T
This processor socket has the pins in it, and the processor has the socket holes. The older Socket 478, had the socket holes, while the processor had the pins.

You need a Northbridge chip that will support the Q9650.
IF, your motherboard has an LGA 775 processor socket, I'm willing to bet your Northbridge chip is an Intel one.
This is a list of Intel chipsets. I have saved the link, to come up on Intel chipsets, that are for the Intel Core2. Match your HP motherboard's, Northbridge chipset, up with the one's listed on this chart. Look down the left column under the heading -> Chipset. After you find your chipset name, look across to the right. See if this chipset supports -> Core 2 Quad.

Example: The 945GC chipset supports Pentium 4, Pentium D, Celeron, Core 2 Duo, and the Intel Atom processor. Does not support Core 2 Quad.
The P965 supports (Uses) Core 2 Duo, and Core 2 Quad.

You may find that a BIOS Upgrade is needed also.

Another way to find out your motherboard information, is to download (Free) CPU-Z from CPUID.com,
Info on Wikipedia:
http://en.wikipedia.org/wiki/CPU-Z
Homepage:
http://www.cpuid.com/cpuz.php

After you have downloaded this tiny, little program, and it is open, click on the Mainboard tab.
This shows a brief video on using CPU-Z,
http://www.utipu.com/app/invited/id/eb8edfb0c6514d459d34d39be30a5028