upgrade or downgrade?

Was thinking about selling my dual g5 powermac and the cinema display, since it's out of warranty, and buying one of these intel imacs. Will I be dissapointed or happy with the performance. Id hate to be actually downgrading, but id like to play a couple games.

im guessing im in the wrong forum

No, but it might be nice to know what the specs of your G5 are, and those of iMac you were planning to buy. Otherwise we'd just be guessing.

i have a 2.5 dual g5 with 160gb hardrive superdrive with 2.5 gb ram with nvidia 5200 geforce graphics card. im not sure about the imac. maybe i need to know what would might perform similar or better than my g5

if i was you I'd keep the g5, they are very reliable computers, I've has mine for 3 years and nothing has gone wrong...I wouldn't just sell it cause the warranty ran out if that is the only problem.

I had a Dual 2.7GHz PowerMac G5 and a Core Duo 2GHz iMac a few months ago and did some benchmark testing.
The Dual 2.7GHz had a downgraded video card but got the same (actually a few points less) score when i compared it to a 2GHz CD iMac. That iMac is now 2 generations old.
I would say the iMac may be a little faster than the PowerMac but not by much. IMO, i'd stick with the PowerMac and save some cash.
Comparing geekbench scores which only factor in processor speed and RAM, the only iMac that beats the Dual 2.5GHz in their benchmark testing is the 24" 2.8GHz w/ Core 2 Extreme processor. The iMacs with the 2.4GHz processors are even with the PowerMac Dual 2.5GHz.
Just before I hit the submit reply button I had to take a step back. I don't remember a normal Dual 2.5GHz PowerMac. I know there is a Quad 2.5GHz PowerMac. It was the last model built before Apple made the switch to Intel processors. Is that what you have, the Quad 2.5GHz?? (It has 2 processors but it processor has 2 cores just like the Mac Pros do.)
If that's the case, I'd certainly keep the PowerMac. That's still worth some good money and will serve you well for a LONG time.