which one to go for canon EOS 450D/400D/ 1000D nikon D60/D80  

All fine cameras. If your budget stretches to the higher-end models, then you should choose between the 450D and the D80. However, if you expect to use your camera in low light conditions, then the Canon has very much better control of noise at higher ISO settings (Nikon has since adopted the CMOS sensor and the D3 and D300 match of exceed the Canon's clean images). I also like to be anble to shoot at 5 frames per second for sports and wildlife.
The truth is, it will be some time before you will outgrow whichever camera you choose, but during that time, you are going to build up a range of accessories like flash guns and lenses and remote release cable etc. When you are ready to move on to another camera, you will want to take these with you, which pretty much locks you into one.
the best camera is the one you can stick with: don't buy anything until you have handled the camera: go to a reputable retailer and put the camera to your eyes (there is a big difference in the brightness of the viewfinder and its comfort for different users, not to mention the usefulness of the information you can see in it); try out the menu and the quick access buttons, and check out how it feels to use - that's a personal thing - and get a knowledgeable salesperson who is not committed to either brand to go over the features with you. Shoots a few frames and compare the results side-by-side.
And if you are a fan of live-view, try that separately: it can be pretty tedious to use on some cameras: enough to sway your decision.

Do not be swayed by what "most people use" (which is Canon, by the way - in both professional and amateur circles, with about 1/2 of all DSLR sales; Nikon has about 1/4 and the remainder go to a flock of about 6 brands like Pentax, Sony etc.) - there is little to choose between similarly priced cameras, though Canon does tend to be cheaper, feature for feature than Nikon. What really counts is how the camera works for you!