Thanks Sir Beane, what I thought no other options.

One other question if I installed the game on a third party machine with an active connection getting the activation code from steam. Then copied the installed files to my machine and edited the registry settings to account for the activation (I assume the activation is stored somewhere there), and then deleted the installation from the third party machine to avoid a requirement to buy the game twice, would such an approach:

1. be legal (most important!);
2. be technically possible;
3. and would any further connection be required if not re-installing and only playing sp off-line?

Any advice appreciated.