The G5 is considerably faster, but considering your applications, you won't really notice it. Statements such as "64 bit is only faster with 64 bit applications" are patently false. Any processor intensive applications will see an increase in speed, though it will not necessarily be a doubling, as one might assume. Because the processor is responsible for performing calculcations when performing any form of rendering, 64 bit makes a huge difference. It means during every cycle, the processor performs a calculation 64 bits long, as opposed to 32. Add that together with improved hardware since the time of your G4, and you end up with a much much better machine, provided you use any sort of application that is that processor intensive. For Warcraft and Word, you don't need a G5. Hell, you don't even need a 1.5GHz G4. Stick with what you have, and upgrade when you can afford a much faster machine.
To demonstrate the speed of the G5, my boss always uses the story of one of our major customers. When the G5s were first announced, he ordered a dual 2.0, with a gig or two of ram. He does the video rendering for one of the colleges at York University. On his dual 1.25GHz G4, it took 9 hours to render his video. He'd done substantial upgrades before, and it usually only saved him half an hour to an hour. So, he sets up his G5, sets the rendering, and goes upstairs to make himself a cup of tea. Just for fun, he decides to go back and watch the bar move for a bit. He gets there, and the screen looks as if he hadn't started it. He checks to see if anything's frozen, and everything is perfectly responsive. It took him 20 minutes to figure out what had happened. It had rendered in the 20 minutes since he'd set it going, and was done when he'd gotten back.
