Intel 915 chipset mobo?

Anybody out there been brave enough to try anything apart from a standard P4 CPU in 1 of these motherboards? I was thinking along the lines of a P4 D, C2D or C2D quad.

The reason I ask is that we have a partially sighted user with a P4 3.4GHz CPU 915 chipset mobo and with both Supernova (screen magnification software) and Dragon Dictate running the system is quite clearly CPU bound. I've improved the graphics response within Supernova by getting an Nvidia Quadro card for the user which has improved things.

Now the obvious answer is to give the user a higher spec desktop but the bounds of the contract means that we're not allowed to do this so I was thinking of just getting a better CPU and seeing what happens but before embarking down this road thought I'd ask here.

Some more info the PC is running 1gb ram, upgrading ram is not an issue but the tests I have done do show that the current ram config is not really an issue.