G5 Worth?

I have a single chip G5, 1.8Ghz w/23" Cinema HD Monitor. It have Mac OS 10.5 installed and install disks for it. I think it has 2Gb RAMM and 120Gb HDD. Airport thing for wireless, keyboard, mouse, and original boxes and packaging.

I would like to know, in everyone's humble opinion, what this might be worth.
Everything works awesome, no dead pixels, only thing wrong with it is, it is outdated. Has been well taken care of.

Thank you for your time in reading this...

phoenixsan said:

what if you have the non PCI-X version of that machine, you can get $200-$350, the PCI-X version going for around $250-400. Add $350 for the monitor. If you had take good care, you maybe dont have cosmetic issues. So, IMHO, you can get around $550-750 gross. Net can be tricky based in shipping costs/fees

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How do I know if it is the PCI-X version? If I upgraded this with another CPU, do you think it would be worth it? I see them on eBay for around $100.00.

Thanks for your time.