News Update:

after burning at 4x 100 memorex dvd-r i risked it again with 50 fuji dvd+r at 8x and must admit that the 4x mode is no good with dvd+r but 8x does ok with dvd+r on these drives. now it's the last time i buy ide drives since that interface barely supports 11 MB bandwidth necessary not to mention 16x. so from now on i get sata burners if i must go for these speeds. thanks everyone for all your kind advice, and hope i too can be of help in the future.

:-)