My problem, in short, is the same as this guys a few threads below, except that I'm using an external Memorex USB 2.0 Burner! I'm pretty sure its not the Burner, because it was and still is (just tried it) working on other machines without problems!
On the important machine the writers hardware buffer jumps up down, therefore lowering the writing speed. Its and P4 1700mhz, low qualilty system, 128mgs of ram, which should be enough (saw it working a similar machine), nero 6.3.xx and win2k / winxp, harddrive fresh defragmented! (anyway, the read buffer is always up)!
I would have to guess Nero is the problem here as the program is a memory hog m8. Does your motherboard support USB 2.0? If not then you should purchase a USB 2.0 PCI card to get USB 2.0 transfer speed m8. Try some free buring applications like DeepBurner or burnatonce 0.99b and see if the buffers jump all round'.
Asus K8N nVidia nForce3 Pro 250 GB, Athlon 64 3200+, Hitachi 80 gig SATA 150, Corsair XMS 1 gig PC4000, ATI Radeon Saphire 9600 Pro (256 DDR), Windows XP Pro (64 Bit),Lite-ON SOHD 167T,, Plextor PX-712SA,BenQ 1640.
Anyway, this Board supports USB 2.0 100%, its onboard, just because of the fact that Nero lets you chose 40x! With Usb 1.1 it'd only be 4x or so, and the device manager says 2.0, too!