[LUGSB] Disk backup

[Akshat Aranya]

Hi,

My laptop's power input is flaking out and I might need to send it in to 
HP.  Sometimes I cannot even power it up.  Because they're going to wipe 
my hard drive, I want to backup the entire drive.  Ideally, I'd like to 
take the dump of the entire disk image so that I can restore it when the 
laptop comes back.  What would be the best way to do so, assuming:

a) I can power up the laptop and boot into Linux
b) I can't power it up at all

Also, it's a dual-boot system, so would a disk image backup/restore work 
fine, i.e. will I get back to the original state without any problems?

Suggestions, anyone?

Thanks,
Akshat