Good call, I'm a newbie to this kind of stuff so anything helps me at all really thanks for that Sir jay see.
Will the GTX 660 Ti outperform the GTX 670? Specifically, will it out perform that specific gigabyte gtx 670?
Nope, it will be slightly lower performance probably but the performance per dollar
is much higher. It's also important to keep in mind that any FPS over 60 is really irrelevant (unless you're running 3D) as it's widely accepted as that's the highest frame rate an eye detects.
I see the monitor you've picked is a 3D one, if you intend to try 3D gaming I would stick to the GTX 670.... but be prepared that for perfect gameplay you may need more power (eg. SLi'd/two GTX 670's), see comments below about the monitor....
Yeah also good point on Windows 7, made up this "wish list" so i could get the foundation more or less figured out, probably won't be ordering for another month or so alot of stuff is up for change .
You could always grab the Windows 8 Release Candidate/Release Preview
to see whether you like it, then decide which of the two OS' you would like to buy.
What's the difference with the modular PSU?
Modular power supplies are really useful, they allow you to only attach the power supply cables you need (inside the case). It keeps everything much tidier which normally improves airflow, along with making it much easier to assemble your PC. These days, a non-modular PSU probably indicates it's either a cheap or old design.
The monitor i plan on running with this is the BenQ XL2420T btw.
Personally I would not bother with a 3D Ready monitor at this point, the technology isn't really at the point where it has become widespread yet so there's a mix of a few well setup 3D games along with a shitload of halfassed attempts which really suck.
That screen isn't too bad in general, but personally I would go for an 'IPS' screen as they (among other benefits) have better, more accurate colours and don't suffer from the same bad viewing angles as 'TN' panels. Probably the most popular screen of that size/type at the moment is the Dell U2412 which has a better panel tech and a marginally higher resolution $399