Flash Sync
D40: 1/500
D40x: 1/200
ISO
D40: 200-1600 1EV steps + HI1
D40x: 100-1600 1EV steps + HI1
Frame Rate
D40: 2.5 fps
D40x: 3 fps
Plus the 4MP more.
Your paying quite over a £100 more for the D40x from what i could see quickly browsing, its not listed on any of the sites i buy off, only the normal D40.
Personally i would say it is not worth it, especially if its for beginner stuff. You will find yourself pushing
your photography knowledge, not the camera's. If you get me..
I have had my D40 for over a year now, and it has lasted me fine. I have learnt alot from it and I am now at the stage of looking for a new camera, not sure how to afford it but blah! With the 6MP i can still print A4 without worrying, i am doubting you will need to print larger?
General rule when buying, never worry about MP really, as long as you are past 5-6MP then it will absolutely fine. Almost all SLR's now come with 10MP+ as standard anyway.
I guess your best bet would be to go to your local jessops/camera store and try the cameras out. See whether you like the feel and try different brands. I am a Nikon man, but i know many others on here are Canon lovers(clearly no idea

). These two brands have the best selection of lenses really so stick with them. Although there is a big rage about Pentax atm. Not tried one myself.