shouldnt the data transfer rate for USB 2.0 be consistent on all applications

So my wife's 1.83GHz CD MacBook died a couple of weeks ago. Instead of patching it up, she opted for me to replace it. I chose for her a 13" MacBook Pro. I love the thing and i am envious. So, our iMac had a kernel panic and my wife thought it was the HDD. we went and bought an inexpensive 500Gb Seagate External HDD. I backed up the iMac manually. The information window said it was going to take 4 hours to transfer 80Gb of info to the external HDD. My MacBook wasn't much faster. However, when i manually backed up her MBP, it took 9 minutes for 20Gb. Is there something different that is affecting the data transfer rate. shouldnt the data transfer rate for USB 2.0 be consistent on all applications?

BTW, i hooked the EHDD up via USB cable directly to each computer.

idk how old your macbook and imac are, but there's probably a faster FSB and newer components in the new MBP, which cut down on read/write times. Also USB 2.0 itself is never that consistent. It can vary depending on the size of files being transferred.

those things never really tell the truth. Sometimes if you actually watch it, it says 15 minutes to go, but about 25 seconds later, it goes down to 14. It's really variable. I believe you are A-OK, but if it bugs you, you can always get it checked out at the genius bar 8)

Maybe the iMacs hard drive is on it's way out and that is why it's taking so long. Maybe that is the cause of the Kernel Panic also. I know when drives are struggling to read it can take forever to back it up.

deus - i theorized that it might be the FSB. The iMac is a G5 w/iSight.
Fish - it actually took 9 minutes for the MBP and i quit waiting after 20 min on the iMac. I am pretty sure it took 4 hours.
DTrav - thanks for the info. i really hope it is not the HDD going and it was some freak occurrence.

i think if the HDD goes we are going to replace it with mini and hook it up to the tv wit a BT Mouse and keyboard.

I have the 20" iMac G5 iSight and file copy using Firewire drives at least seems just as fast as my Intel C2D Mac.

I never use USB unless I have to for copying files or backup as it's just too laggy.