Mixed feelings about upgrading

At the 'French Café' by the lakes in Copenhagen.

I bought the Canon 20D a few weeks ago to replace my 10D. The latter was at Canon Denmark to have the chip cleaned. And then it struck me: Maybe I should sell the 10D now when it's faily new and people are willing to bid on it. In a few months or half a year I will not get a lot of money for it. The plan worked out fine, and I could use the money to finance half og the 20D.

I have now been around the new functions and I am happy about it. It's fast, a bit smaller, the lcd-screen is better and faster, the output is 1.9 mpix better and the buffer is a lot bigger. But I cant stop thinking - is this a new camera or is it just an upgrade? The 10D made super photos! Sure, there was some limitations, but all in all I don't make visible better photos now than before. It is an expensive upgrade! The next one in the line is the 1D mk2 which is above my budget.

Give me your thoughts on the never ending story: buy-upgrade-buy or upgrade-get the newest model and so on....