What is the Nikon equivalent to the Canon 50d?

I'm a long time Canon man. I have recently decided to switch over to Nikon because all i hear is that the glass is much better. Also, the affordability factor plays a huge role. My question is when I do make the transition what body is a good equivalent to the 50d? Not in price but in power. If you have any other recommendations such as lenses or other accessories it would be greatly appreciated. Right now all I have in my bag is the 50d, rebel XTi, Canon 70-300 standard, Canon 18-55 IS, Canon 28-135 IS USM, and Canon 580EXii flash.

Added (1). Also are there any things I might need to know about Nikon? As I said I'm a Canon man. Don't know much about Nikon.

The glass is not "so much better" that you should just drop what you have and switch. Both companies make very good lenses and accessories, you just don't have the better Canon lenses to see that.

If you must switch to Nikon, the D90 or better the D300 would be the place to start. If you buy the same level of lenses, you won't see any difference in your photos. It isn't as easy to differentiate the high end Nikon lenses from the mid and low grade stuff, they don't make it simple like Canon where you just look for the L in the name.

Instead of switching brands, it may be a better option to upgrade your lens collection. Get a couple of L models, say the 17-40 F/4L and one of the 70-200 L models that suits your budget. Try those for a while, and if you still feel the need to switch, you will get a much better price for your Canon collection with L lenses in the bag.

The Nikon D300s is close to the 50D

The glass is about the same. Where Nikon lenses excel is in the auto-focus arena.AF-S lenses are ultra fast when auto-focusing and important if you are shooting sports.

Here is a sample shot with the older D300 using a AF-S 300 mm f/2.8 VR lens with the VR feature turned off.

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For the best low noise at high ISO, the Nikon D3 and D3s are the best.