If you're running a G5 Mac that means that you have a Motorola - not Intel - CPU powering your device and Boot Camp won't work for you:
Apple's Boot Camp software, included with Mac OS X 10.5 Leopard, lets you install and use Microsoft Windows and Windows-based applications on your Intel-based Mac.
To use Boot Camp with Mac OS X 10.5 you need the following:
An Intel-based Mac
A Mac OS X 10.5 Leopard installation disc. This can be either a Mac OS X Leopard disc included with a purchased copy of Leopard, or a Mac OS X Install Disc 1 from a Mac that had Leopard preinstalled
A USB keyboard and mouse, or a built-in keyboard and trackpad
At least 10 GB of free space on the disk you’re installing on (for Microsoft Windows and Windows-based applications)
Boot Camp Assistant, which is installed by Leopard in (/Applications/Utilities/)
As well as Microsoft Windows:
An authentic, 32-bit Microsoft Windows XP Home Edition or Professional with Service Pack 2 or Service Pack 3 disc
An authentic, 32-bit Microsoft Windows Vista Home Basic, Home Premium, Business, or Ultimate disc
With some Mac Pro or MacBook Pro computers, an authentic, 64-bit Microsoft Windows Vista Home Basic, Home Premium, Business, or Ultimate disc
I tried Virtual PC years ago and it was terrible. Maybe someone else will chime in here as I know I have read before that some here do use it.
Best advice? Trade up to an Intel Mac with Leopard, a no hassle sure thing for running Windows.
Yep. Get A Intel! Best Thing You'll Ever Upgrade To!
1.33 GHz iBook G4, 10.5 ; PowerMac B&W G3 400MHz, 10.4 ;1.66 Ghz Mac Mini Intel Core Duo, 10.5
Bill: What's That
Steve: A iHouse
Bill: But It Doesn't Have Any Windows!