Can I run Windows XP Pro SP3 on my PowerMac G5 1.6 GHz computer with 80 GB Hard Drive and 1.25 MB of RAM?

Nope, sorry, only on intel chip machines, not G5 machines.

No. You need an Intel-based Macintosh in order to install Windows through Boot Camp. The Power Mac G5 uses a PowerPC "G5" processor which is not compatible with x86.

You can use emulation software like VirtualPC or Q (http://www.kju-app.org/) to run Windows, but the experience will be very slow.

Thanks for the quick response on the Windows question. I had feared that might be the case as my previous experience with the G3 showed that I got to run a V E R Y S L O W version of Windows 98 on the Mac but it was like pouring refigerated mollasses in December. In other words, glacially slow and not worth the time spent.

Bill

I wouldn't recommend emulators, I spent about 6 hours installing XP on my G4 to find that there was an activation error.

Emulation is much slower that virtualization.
Virtual PC should nowadays be free, but also Q might be an option (http://www.kju-app.org/) even though that won't get it to virtualization or native speed either.
If it's only a few applications you need in XP, those might be worth to try though, instead of selling your current Mac to upgrade to an Intel one.

PS: I think you meant 1.25gb not 1.25mb, Lol