GeForce 7900GS/GT Buying Questions

I have an AMD Athlon 64 3700+ with 2 512mb Kingston value ram, and a Nvidia 6600 MSI PCI-Express. I have two 22inch widescreen displays both DVI, and I was thinking of upgrading to a dual DVI Card, since the MSI card I have currently only supports one analog and one dvi.

What I use my computer for: Business mostly, graphic editing/coding/multiple websites open at once, tech support (which is why i need the dual 22in displays), however probably for about 2-4hrs each day I do play video games, ANNO 1701, Medieval Total War 2, and World of Warcraft are the current games I play. Now all of these games play decent, but I have to turn down the settings and the graphics don't look that great.

I was thinking of upgrading to either a XFX Nvidia Geforce 7900GT or a XFX Nvidia Geforce 7900GS Here's my questions, now according to Tom's Hardware's VGA ChartsThe GeForce 7900GT TOP outproforms the GeForce 7900GS in every category by a fairly large percent, usually by 20fps, or something like that.
What I'm wondering is, is the GeFoce 7900GT Top the same as the XFX Nvidia Geforce 7900GT from newegg?
Also, is there a difference in brands? Because Zip Zoom Fly has the GeFoce 7900GT from MSI for $200.00 as well, Whats a better brand to get MSI or XFX?
What card would you recommend me getting the 7900GS or the 7900GT?
Am I going to notice a huge difference over my old 6600?
Thanks in advance.

Ugg tomshardware.... they are notorious for putting the most random revisions of cards in their lineups for some random reason. Basically the 7900gt top is a pre overclocked 7900gt* and thus performs better then a reference clocked 7900gt. Again it would be sane if tomshardware put a normal version of the 7900gt and then an overclocked verison to see the difference but no thats just how tomshardware has to roll. If I had to stick to nVidia and was making the decision myself I would pick up a 129.99 7900gs or 79.99 7600gt. The cost of moving from a 7900gs to a 7900gt is not worth it IMHO.

*the 7900gt you linked to at newegg has a speed of 450mhz core / 1320mhz mem where as the 7900gt top, the only single 7900gt that tomshardware has on the vga charts I might add, is at 520mhz core / 1440mhz mem. The true difference in a 7900gs and a 7900gt is smaller.

edited to add cyber deal links.

Hrmmm, for that price I think I will just do an SLI setup with two 7900GS's

Edit: Should I get a vga cooler for the 7900GS? How well would an SLI setup work with dual monitors? I heard their were problems with SLI Setups and dual monitors.