I went and found The Orange Box for a bargain price of £19.99 ($40USD approx), so I got it.
I reinstalled Steam just a couple of weeks ago or so and although I said I wasn’t going to bother playing games on the PC, I’ve found that it can handle things quite well with the 2GB of RAM and X700 gfx card.
With only a limited amount of HDD space, I’ve backed up a load of stuff onto DVD’s and cleared around 20GB which is pretty much what’s needed to install The Orange Box apparently. I’m looking into getting an external enclosure for my old 200GB HDD as it seems a waste to just let it sit in the old PC doing nothing and my new PC doesn’t quite have enough space to install it as a slave drive.
So, now to defrag and install The Orange Box…