I'm a Canon person as well, and extremely happy with my 350D (Rebel XT). But I have friends who are very happy with their Nikon D-SLRs. If you have some lenses already, Nikon's probably the way to go, since you can't use the lenses on other cameras as cpx said.

Check DP Review for reviews and such if you haven't been there.

You also need to take into account lens quality, the type of shooting you'll be doing, and what you'll be doing with the images if you're considering waiting for more megapixels. If you have lower-grade lenses and/or will mostly just be putting pictures up online or making prints that aren't huge, 6MP is quite sufficient. If you have professional grade lenses or plan on blowing up prints, you might want more than that. Also remember the 1.5x crop factor on the consumer/prosumer-range Nikon D-SLRs; if you're using a lens that has optical abberations at the periphery (but is more decent towards the center), the crop will eliminate that to a decent extent. (And you'll get far better pictures in any case than pocketable cameras with a pointless 8-10MP that have nowhere the optics and sensor size of your D-SLR, even at the lower pixel count.)