Finally went and ordered new HDs.
500GB WD Caviar Black and 1.5TB WD Caviar Green(64MB cache model).
Over my old WD 160GB IDE I hope it will show some improvement. And yes, no more balancing on the edge with space!
There is an unused but opened Radeon HD4850 in the place I work at that I might be able to get with 50€. I have X1600pro in AGP, worth it?