There are actually 1 feet cables just for this but 3, 5 feet or even longer doesn't seem to make that much difference to me. A cable with those "blocks" around them might give a unsignificant better picture.
(I actually use 2 cables in the 5-10feet region (both with blocks) from my scandoubler and Voodoo3 output trough a switchbox and then to my monitor and I can hardly see the difference from that and to just plugging the monitor right to video output.)
