Will Windows 7 run on an older PC?

Windows 7 will run just fine on your old system. But you won’t be able to run Windows Aero theme(depending on your graphics chipset), although the OS itself will run perfectly fine. You should upgrade if you want to game or do intensive work on your system. Simply upgrading your graphics won’t improve the performance of 3dsMAX or Maya. It will also need an overall upgrade - CPU, motherboard, RAM and more. The graphics card will only help while working in the viewport and on high density wire frames - it will be smoother than it is now with all kinds of mesh and turbosmooth modifiers turned on. The rendering, however, is done only by the processor and memory. When you upgrade, don’t look for a graphics card any slower than a GeForce 9600GT.