Graphics Card: Nvidia 128Mb
I think this is your main problem. Apart for the fact the card is unknown (if it's one of the "turbo cache" cards, like the 7600, the performances are absymal), 128MB is probably not enough with a scenery like Geneva, which uses mostly hi-res 1024x1024 texture everywere.
If textures needed for a scene do not fit entirely in the VRAM, the performance decrease is not smooth, but it drops immediately.
You can try lowering your Max Texture slider a notch or two. One notch down will use 512x512 textures, meaning the video requirement will be 4x lower. Two notches down it's 256x256, 16x less memory used.
Of course, the scenery wouldn't look as sharp but, it's either this, our upgrading the video card. 512+ cards are quite cheap nowadays...
Hard Drive: 40Gb (Approx 1.7Mb Free)
This might be an issue as well. An old hard drive (40Gb is probably 4-5 years ago, right ?) might be inherently slower than the newest models, but it also wouldn't work very good with so little free space left.