ShopTo.Net

Wouldn't use anyone else for pre-orders

I have used a lot of websites for ordering games, and have found shopto.net to be one of the easiest to use, and with prices as good as theirs, I would recommend this site to anyone.
They also guarantee that pre-orders will arrive by the release date at the latest (or they'll credit your shopto account with £5), so on two occasions that I have pre-ordered, I have had the games before they're out in the shops (Resident Evil 6 was released on a Tuesday....I had my copy on the Saturday before)!
All in all, unless I find a product significantly cheaper elsewhere (which isn't often), I would use shopto.net every time.