Free with Windows Vista (The Official Magazine) February 2008 issue (£4.99) is a Laplink USB 1.1 cable (worth £19.99 they say)
I think this offer is from Sainsbury's only (so it says on the magazine front cover).
I have to be honest and say I have never used Laplink but I believe the software is used to move data from one PC to another easily. If you plug this cable into the USB ports of two PCs you can then use Laplink software to move the data.
Here is the laplink site: http://www.laplink.com/
If anyone has used Laplink (or PCMover or PCSync which can also use the cable) then maybe they can give a bit more info.