Well Stealth...if games use PS 1.4 shaders, then yes,..all current NVidia cards, except the NV30 ones, will perform pretty poorly, or look pretty poorly, depending on how the developer chooses to solve the problem.
There is a compelling reason to use 1.4 pixel shaders, as it is completely forward compatible with 2.0 and later. Keeps us dev guys from reinventing the wheel all the time.
I have about 40 or so pixel shader routines in 1.4, that will find thier way into my software. What I am doing is disabling them when I detect a card that does not support them, rather trying to do it in software.
Doing it on the CPU side means a heck of a lot more code and thus creating a major performance bottleneck.
While 1.4 shaders are not a huge part of the market today, we dev guys are working on stuff for a year, or more, from now. ATI's 8500 and all later cards support 1.4. The NV3x and later lines appear to support 2.0+, so 1.4 will work for them.