I have a 5 meter DVI-D dual that I have spare. The dual is a standard that comes out of the video card, but some monitors can only accept the DVI single.
goto www.lindy.com . I have their 7.5M dvi cable and it is an excellent performer (1366x768 resolution). The price is reasonable too. This is about 25ft.
No i am not affiliated with them just a happy customer. You hear so many complaining about sparklies at higher resolutions, especially on longer cable runs. Lindy guarantees their cables for 1080i at that length. 10 meters and above is when people are starting to push it.