[Solved] More cores or less cores? Major multitasker.

I do a lot of website developing and usually have a lot of browser windows, text editor windows, spread sheets and flash movies open at once. If it makes a difference I'm running the Windows 7 32bit Ultra Release Candidate.

The problem is I have an old 2.8 GHz dual Xeon machine (With 2 GB registered ECC ram) that really needs to be upgraded but most of the program I use are single thread only. Will upgrading to a machine with multiple cores really speed up my computer?

For example, what's better when running single core aps:

phenom x3 8750 (3/9950 = 2916.66667)
or
phenom x4 9950 (4/9950 = 2487.5)

It seems to me that the x3 would run faster for me than the 9950 would.

Would I even see much if any improvement moving from a dual XPU 2.8 GHz xeon to a Phenom in non 3d applications.
My processors spend a lot of time running at 100% when I'm crunching numbers or have 40 browser, spread sheet, and text editor tabs open. Only having 2 GB of ram does not seem to be much a problem. I rarely see it go above 75% usage... Unless firefox starts leaking. At any one time it's not unusually for me to have XAMPP, UltraEdit, FireFox, Chrome, IE8, Excel, and Safari open and doing something. It's when I start running large MySQL queries, running several flash videos, running Excel large calculations that I wish I had a faster PC though, and all of those programs only use a single core at a time. The only time I ever reach 100% on both CPUs is when I play a heavy duty game or when I am waiting on a large query or PHP program to complete a task while also doing something else... Or if I'm using chrome for a lot of stuff. That program seems to make good use of both CPUs

Thanks, I was trying to ask about 4 cores vs 3 cores for the Phenom II. My question got a bit wordy. I already have a good idea about what I need for a system build.