I'm interested in using aperture but have a G4 1.25 ghz tower. Am I right that aperature will only run on G5 towers and G4 powerbooks? Anyone running it on a G4?

Aperture relies heavily on the graphic card, so if your G4 has enough RAM and one of the graphic cards listed on Apple's Aperture page (here) then it should run (but not fly). I doubt that you'll be happy with the performances, though. A G5 tower with good graphic card or a new Mac with Intel chips is the way to go.

The demo version is free, so download it and try it.

Aperture does a hardware check and will refuse to install on a G4 desktop machine. There are workarounds to this ("hacks") on the web, but my practial recommendation is to get new hardware (Aperture really does run best on Intel hardware) if you want to give it a real shake.

Right,
My experience is that if you want to have decent performances then a new Intel-based Mac or at least something like a dual 2.0+ G5 with an good or excellent video card is needed. I''ve seen Aperture run on a Mac Mini (G4) but frankly it was not pretty!

Apple has the required specs here.

http://www.apple.com/aperture/specs/

I am running Aperture 1.5.2 on my 17" PowerBook with 2GB RAM. There has been no speed issue, display issue, nor any "hangs". The only speed issue I have experienced is on my external USB 2.0 hard drive. That is really slow. I had a Lacie D2 which crashed. I pulled the Maxtor hard drive from inside and installed it in a USB case, etc. Going from FW 800 to USB II is a real downgrade, but $$$ talk and I did not get another FW drive.

I attended the hands-on session for Apple in Boston and feel that Aperture is the best damn DAM on the market now.