Listen up. There is no point playing Mass Effect 2 before playing the original. If you do, the Normandy will be just a ship. Wrex will be just another Krogan. Plus the story is infinitely, unbelievably better.
You must - must - play the original first! If not, you're doing yourself out of one of the greatest interactive storytelling experiences of all time.
Now that I've got your attention, Gameplay are selling the original for £3.99 on PC. This is a quid cheaper than the GAME network and over £4 cheaper than anywhere else. Have a PS3 and a PC? For the love of stupid jellyfish, treat yourself to this first and enjoy the series as it was intended.