Assuming you are using DVI, the maximum recommend distance is 15 feet or 5 meters. 75 meters is excessively (15 times) beyond the recommended limit. It can be done, however, it will be expensive to do so.
Solution:
Gefen DVI DL Booster PLUS = $249 + the cost of the cable
- Support for 2560x1600 resolution
- Maximum range is 200 feet
http://www.gefen.com/kvm/dproduct.jsp?prod_id=4999
75 meters = 246 feet
You will need to buy two of these devices for a total cost of $498 (excluding shipping & taxes) for your setup to work properly.
This is in fact the cheapest solution.