I find it interesting that i am seeing more and more people who are buying their first (D)SLRs are buying Nikon. This is a stark contrast to just a few years ago. Canon has lost 50% market share in the lower end, but the majority of pros still shoot Canon. Nikon has come back strong (remember when they had just the D100 and D1/D2 and D70 for such a long time, and didn't release anything?), which is great for consumers.
I also credit Nikons' marketing team, although Ashton is still a tool; which is ironic, as that is what cameras are!
Only you can make a decision that is right for you. For me, I don't buy into all the gimmicks that they use nowadays. I really like my camera and get great prints from my gear. I think megapixels still is a huge selling point, but video is quickly catching up as a deciding factor.
I don't use video, so I couldn't care less about that. I don't use a high frame rate (it is nice to have, just incase..mine shoots 6.5 fps), and I don't usually shoot above ISO 400. Thus my next camera is going to be a 1DS2 MK2, or perhaps a 1DS3 if the price drops enough, and Canon prices the 1DS4 at $6500...
As far as buying used, that is all I do. After buying a 30D new ($1500) and then selling it 6 months later for $800, I vowed never to buy new again, and I haven't..err, i did buy an XSI new, but i got the XSi+ 18-55IS + 50-250IS for $720 new. Sold the XSi for $400, the 18-55 for $100 and the 55-250 for $180, so i didn't make out to bad. Also bought a Sigma 10-20mm for $250 and sold it for $350..