Hi,
The iBook G4 is not an Intel Mac, so you cannot use it to run Windows natively using Apple's BootCamp software, nor can you use Parallel's Desktop for Mac software.
So your solution to use Virtual PC is the only real solution (though it will run slow).
You just need to make sure that you select Virtual PC for Mac (and not the Windows version) :
Actually, you need to choose which edition you want first :
http://www.microsoft.com/mac/products/virtualpc/virtualpc.aspx?pid=whichver (XP, Win2000, ...)
And you will need the update to version 7.02 :
http://www.microsoft.com/mac/downloads.aspx?pid=download&location=/mac/download/ misc/vpc702.xml&secid=100&ssid=3&flgnosysreq=True
Then you can burn the downloaded files on CD (with your PC) and take it to your Mac, copy the files to your Mac and run the installer(s) (or if it opens without running an installer, you just move the application to your applications folder)
iBook G4 Mac OS X (10.4.7)