Canon 20D or Nikon D70.
The 20D will be slightly higher, probably in the $600+ range for just the body. Slightly higher MP at 8.2MP and better high ISO noise. (and, no, I'm not selling mine)
The Nikon D70 is a great starter for the Nikon line, probably in the sub $500 range for the D70, possibly higher for the D70s. It's "only" a 6MP camera but at this stage, you won't see a big difference. Upgrade to the D80 or D200 later, depending on your direction.
Personally, I'd stick with either of those two product lines. Fuji and Sigma's newest are interesting specimens amongst the DSLR market but Minolta showed how a smaller fish in the digital market can flounder and die. Sony saved the Minolta line but I wasn't overly impressed with their intro to the market. The next few years are going to be interesting in the lower end DSLR market. Canon and Nikon, however, are unlikely to go anywhere.