So, I went to post a game, and having recently discovered that I can use PGN files to post it instead of playing out everymove (that's correct right?), I tried to save/open the PGN of the game. However, windows did not recgonise the file - what software do I need to open it?

You can use notepad or most other text editors.

You can get Chessbase Light, SCID, Winboard/Xboard, Arena, Chesspartner, Fritz, Dasher, Chessmaster - the list goes on and on.

Arena is free and pretty nice.  :)

I believe it's on www.playwitharena.com :)