The G450's fifo buffers aren't terribly efficient compared to newer designs. And if your system is PCI-E any G450 version would not have nearly as much bandwidth.
It might be faster now, but even a Radeon 46xx will clobber it once drivers are far enough - and they might be already. In the Gallium3D era, there will be absolutely no contest.
Try a Fedora 12 LiveCD and check out Noueavu's performance. Accd to the wiki GF7 has Xrender acceleration through the 3D system and it could be much faster than nvidia's driver nowadays.
If your system has an intel IGP, try that. Dual-channel shared memory can actually be *good* for 2D performance, unlike the i810 days. Even Windows 7's desktop runs very nicely with an x4500 - I'm only going to pop my 4830 back in to play with GPGPU and OpenCL stuff.
Also note that frame buffer drawing can be surprisingly fast with modern CPU's.