??Windows won't start on Acer Laprtop Travelmat 290 running WIndows XP (1 & 2) It keeps saying start windows in safe mode, safe mode with networking, safe mode with command prompt, last known good configuration. I guess it's the hard drive that has crashed??? How difficult is it to buy a new (bigger faster) hard drive and re-install windows? The laptop didn't come with a Windows CD and I have my data backed up, so haven't lost anything.

Give the "last known good configuration" a go if you have not already ,or the safe mode ,
if that is no good
when the pc try's to boot up it should show a key ,such as (F11) that needs to be hit to enter the recovery stage ,what ever it is do it and follow the prompts,this should recover the laptop to its delivered state ,when it finishes you can restore your backups.
however if the drive does not have a recovery partition you will not be able to do it.
So:

it may be that the hard drive is ok but the operating system files have been corrupted in some way,

as you have no windows disc you will need to obtain one to either recover the operating system or re install windows, and you may have to go to the Acer website afterwards for some drivers when you have finished.

good luck
Terry