Have a 20d now, the 30d was nice but not worth the upgrade, is the 40d worth it?

Well with features like a 10.1 megapixel CMOS sensor, New AF system with 9 cross-type sensors, EOS Integrated Cleaning System, 6.5 fps, burst rate up to 75 consecutive JPEGs or 17 RAW images, DIGIC III image processor, Picture Style settings, Spot metering, and a 3.0-inch LCD monitor with advanced Live View Function - it's hard not to be tempted by it.

Here's one comment I found on the 40D you may find interesting: The 20D shows slightly lower noise than the EOS 40D with high ISO noise reduction off, but slightly more noise then the EOS 40D with high ISO noise reduction on. High ISO noise reduction works at all ISO settings and mainly seems to drastically reduce chroma (color) noise.”

So with reduction engaged, the 40D gives you an edge you don't have with the 20. But the question for you is, is that, plus the other features it comes with enough?

I just purchased the 30d, now my 20d is my backup. I upgraded because I needed the larger preview!
I asked for the largest avail for under $2K, was sold the 30d on July 7th and the last of week was in
another camera shop when they pulled a 40d out of the box FOR THE EXACT SAME PRICE with an
even larger screen! Ahhhhh! In my case it wasn't for any other upgrade except for the larger preview,
something needed for eyes of 40!

I bet you considered taking that 30D back the second you saw that 40! And you may be able to!