Stepping up to a digital SLR

As you might know, I love taking pictures! My Canon PowerShot A620 has taken more pictures in the two years I had it, than I have taken with all other cameras together! I’ve never owned an SLR or digital SLR, but I have recently had the opportunity to hold and use a couple of Nikon D80 and Canon EOS 350D and I love the pictures I get! And now I must have one myself! 😛 But which one do I choose? My choices so far:

Any opinions out there? I’ve read quite a few reviews, and hopefully I will try the Sony soon. Lenses are of course vital, and I’ve read very positive reviews about Nikon’s AF-S DX 18-200/3,5-5,6 G VR IF-ED, and it seems it is exactly what I need.