Shaan
Please tell us why you wanna switch. I have moderate experience with both systems (Nikon 1 year, my own 20d came 3 weeks ago), I can asure you (and many other will also do the same), that theese two are the best you can get. In fact, any D-SLR can produce superb images, but N and C are the best.
If you already own some Nikon stuff (and especially good one), then stay with it, IMO it's not worth switching, unless you want magnesium body, 5fps, 65 ms shutter lag, iso 3200, mirror lock-up and custom WB which is what 20D offers compared to Nikon D70s.