So, having had such good results with the SSD I put in my ageing desktop, I decided to get one for my ageing laptop too. I did the copying a bit differently - since the SSD was 50GB smaller than the spinning rust it was replacing, a straight dd wasn't going to work. In any case, it's a bit boring waiting hours for blank space to be copied across. There was only 30GB of actual data.
I connected both drives to another machine - I couldn't get hold of a SATA caddy to have them both on the laptop - and again, booted to SystemRescueCD. This time, though, I used GParted to copy-paste the boot partition, made an empty NTFS "main" partition and used rsync to copy the contents of the old C: drive to the new. Much faster to just copy the data. Some quirk of ntfs-3g or rsync seems to have lost the "hidden" attribute from some files, but otherwise it all worked.
You'll have realised from my mention of NTFS that this laptop runs Windows. The purists may call me a traitor to Linux, but having at least one Windows box around is useful for all sorts of things, and this is mine.
The final annoyance was that Windows refused to boot from the new drive:
A required device is inaccessible
It did however prompt me to boot from the Windows CD and hit repair, which worked. Given how rapidly it worked, I can only assume Microsoft write the UUID of the drive to the boot sector or some such, as a tedious anti-piracy measure.
The SSD magic definitely seems to have made this laptop usable again - previously it was slow to the point of being unusable and you could hear the disk crunching inside it. Hopefully the SSD should give battery life a slight boost and be more robust against being dropped or jolted too.
Since I'm now all SSD'd up, I've got my desktop running DBAN to erase the old mechanical hard disks I've replaced. Did I mention how handy having a network boot server is?