Here's some info:

Mainboard: Intel DG965SS
Processor: Intel Core 2 Duo E6400 @ 2133 MHz

Seeing as I've upgraded just about everything in my computer, and I have a new Antec
P182 case on the way, I'm going to use all my former parts to build my wife a computer.

I plan on giving her the mainboard/processor listed above, and get myself an upgrade over this.

It looks like quad core is still too expensive for me, although this one:
Newegg.com - Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Processor - Retail

seems do-able, I'm just not sure if it's worth the price.

So, once again , I'm reaching out to the powers that be. I need suggestions on a CPU/MB combo that would be an upgrade over what's listed above. Without breaking the bank, of course.

Here's my system specs, for reference:
Video Card: ATI Radeon HD 2900 PRO 512MB PCI-E
HDD: 150GB WD Raptor X SATA150 10,000RPM
RAM: 4GB(2x2GB) Kingston HyperX DDR2 800
PSU: Thermaltake Toughpower ATX12V 650W
O/S: Windows Vista Home Premium 32-bit (I do have XP Pro disk from when I owned an Alienware comp)

yep that quad core is defenatly worth it... you may not notice apps running faster etc because most are just now beggining to take advantage of dual core cpu"s, but you will still be able to run more apps than a dual core cpu.

as for compatibility im not 100% sure if that motherboard supports a quad core cpu .. but give me soem time and ill check

yes looking at intels website it only supports up to core 2 duo not core 2 quad

ill find a few things on newegg... hmm what do you say on budget no more than 450 - 500? total with both cpu and mobo

I'm looking for any mainboard that will support that chipset...as well as the other items in my computer.

The board/cpu I listed will be relegated to my wife's 'new' pc.

Newegg.com - GIGABYTE GA-P35-DS3L LGA 775 Intel P35 ATX Intel Motherboard - Retail

a good mobo
good chipset
no on board grapshics , so you will allways be using your 2900 ( not a problem)

If you can get a motherboard to support that CPU(if yours doesn't already, I'll have to look) It's deinitely a great buy. That thing will last you a while, and be very efficient at running many applications.