Definitely right, the issue is actually this - my usb is detected as sda and the hdd as sdb.afaik this is not possible as devices never gets renamed no matter what you do.
Now I'm quite certain this is a kernel config issue. Slax7 has this problem of the usb being detected as sda. I used the .config from Slax7 to build a new Porteus kernel and when I booted with this kernel, the same issue occrus - my usb is detected as sda. Now if I use the Porteus kernel config (modprobe configs; zcat /proc/config.gz) and I rebuild the kernel, then my usb is detected as sdb and the hdd as sda (which is the way its supposed to be).
I'd like to figure out exactly which kernel config controls this however - any one have any ideas? I suppose its one of the SATA or ATA configs, but comparing between Slax and Porteus configs, I can't see which one makes a difference.