ok i have bought 5 different dvdrom (well i am going to return it tommorrow)
basically i tested for speed (reading dvd-r disks)
here are the top 5
Pioneer DVD120 (started x4)
Liteon 166s (started 3.5x took about 30-60seconds to reach 4x)
Liteon dvd/cdrw combo (started 3.4x took about 30-60seconds to reach 4x)
benq 1650s (started at 3.3 took about 30-60seconds to reach 4x)
LG gdr-8162b (started at 2.5x took about 3 minutes to reach 4x)
i used nero6 CD/DVD SPEED.
used different medias and all gave approx similar result.
reason I put this cause in some country toshiba drive is hard to get. so if you need a dvd rom that can sustain 4x minimum for 4x burning then buy a pioneer DVD120..
PS> i tried dvd video testing (duel layer) and it started at 5x. and used smart ripper as well and speed was very good 5x minimum.