I bought the HK AVR-500 for $500 about 2 weeks ago from Circuit City. Today I was told that they will have the new 510's in stock this week.

I'm trying to decide whether I should:
a) keep the HK AVR 500 : great $ deal.
b) trade up to the HK AVR 510 : MP3 decoding, but is it worth the price diff.
c) go in for a Denon AVR 3300 : can get it for the same price as the AVR 500.

I know there are a lotta factors in play here, such as what exactly I'm looking for, how much I can afford etc etc .. so let me ask the question differently, what would you do?

Thanks!

I owned the AVR500. (had it for nine months) I have had problems with it..... If I were you, I would for sure take the AVR510 over the AVR500.
I was considering trading up for the Denon 3801 myself.....

Best of luck!