Argos have the MadCatz wired 360 gamepad for £6.99 down from £19.99, both online and instore (near the checkouts). If you are in the market for a wired 360 controller or want a cheapish gamepad with rumble for a PC (XP or later) it seems like a good deal.
The pad itself is slightly different in design to the official 360 (which seems to have garnered it some reasonable reviews) - back and start buttons are above the "360", the left and right triggers are "proper" triggers, L and R paddles are a good size and the D pad is a + type rather than round. It feels solid but comfortable in the hand, controls are reponsive. No autofire / turbo bells and whistles on this one.
I've tried it on several GfWL games on the PC without issue (Batman, Bioshock) as well as a couple of non-GfWL games (L4D, Halo after a bit of controller configuration) . It it is detected as a MadCatz controller but performs without issue (W7 x64).