Just a heads up for those who will be getting a shiny new SATA disk 
for Christmas!
I opened my present early and tried to install a new SATA drive in 
with my existing IDE drives. GRUB went into a sulk and wouldn't boot 
the system. Turns out this is a known and nasty problem which is to 
do with the enumeration and naming of the drives. BIOS, GRUB and 
kernel all have different opinions on the matter. In my case the BIOS 
thinks any SATA drive must be number 1 in the list even though I'm 
booting from an IDE drive. This varies from BIOS to BIOS (of course!) 
SO: if you get GRUB complaining about an unreadable disk when you have 
a mix of SATA and PATA drives you too can join the fun Christmas 
party game of 'Guess the GRUB root drive designation'!
LOTS of further details and (yukky) workarounds at
https://launchpad.net/ubuntu/+source/grub/+bug/8497
ATB, Peter