XPS 700 Stock Upgrade Advice Needed: GPU and Processor Question.

I've read several posts, followed the links on both my questions and researched the issue, but still have some questions and I'm still unclear on which way to proceed.

If anyone can help that would be great.  Also if this post is in the wrong area feel free to move it.

I have a stock XPS 700 and I won't get started on the mobo upgrade as I do not have the "well" communicated upgrade.

Anyway, I have a XPS 700 Stock machine purchased in Dec. 2006. Specs are below.

The only  2 things I want to do is 1) Get a new CPU chip and 2) a new GPU card.....all without changing the mobo. i just want to put the new CPU and GPU in and go.

My rig is used for Home Office (Excel and .ppt), Gaming, Correl Photo editing.

1) What CPU can I upgrade to from my current E6700 without changing the mobo?

2) What GPU card can I upgrade to, from my current NVIDIA GeForce 7950 GX2, while retaining the stock set up and new CPU chip?

SPECS:

2.67 gigahertz Intel Core 2 Duo E6700
64 kilobyte primary memory cache
4096 kilobyte secondary memory cache
Board: Dell Inc. 0YF432 A02
Bus Clock: 1066 megahertz
BIOS: Dell Inc. 1.4.1 05/07/2007
Windows XP Media Center Edition Service Pack 3 (build 2600)
NVIDIA GeForce 7950 GX2 [Display adapter] (2x)
ACR Acer P221W x [Monitor] (22.0"vis, s/n LB1090113800, October 2007)
2814 Megabytes Installed Memory
Slot 'DIMM_1' has 1024 MB Slot 'DIMM_3' has 1024 MB
Slot 'DIMM_2' has 1024 MB Slot 'DIMM_4' has 1024 MB

Thanks for your expertise and advice.