Xbox 360 Controller Issue

I bought an Xbox 360 controller (the red packaging for PC) today which is working nicely in PJ64 (1.6). My problem is that I cannot press certain buttons simultaneously. For example, in Goldeneye I have set the R button to the left trigger, for aiming, and the Z button to the right trigger, for firing. If I hold down the left trigger and aim, pressing the right trigger seems to replicate the R button - the aim is cancelled, or toggled on/off with taps. Releasing the left trigger allows me to fire again, but this ruins the point of aiming in the first place as the gun snaps back to the centre.

However, if I set the button in front of the left trigger (LB) to R button, and keep the Z button assigned to the right trigger, it all works fine. It's just when I use the same type or opposite buttons that the issue occurs. I also have LB and RB set to B and A and cannot do the backwards weapon switching trick as it requires simultaneous button presses.

I have tried both Jabo's control plugin as well as the latest N-Rage and it's the same in both. Has anyone had this problem before and found a way to allow simultaneous button presses?

Thanks but after posting I located those after a lot of reading and searching and wasn't impressed. Yes, the axis is split, but it removes part of the right analog stick's functionality, which ruins certain games.

Never mind - it's not a huge issue, just means I have to play with related actions mapped diagonally on the shoulder buttons