Yeah, I guess most of you are right. Get the iMac if that's all you need. Personally, when I buy something like a computer, I buy it knowing that it is fast enough for the most hardware intensive task I'm probably going to do. If it can't handle the task well, then I don't buy it. The most I ever do is sound editing. My PC can't handle Soundforge at a satisfactory pace (it takes 3 to 5 minutes to process every single thing that I do), so I would never buy a Mac that can't handle it either. But 95% of the time, I don't use Soundforge on my PC, so it's good. But it would be such a downer to know that I spent soooo much money on a machine that already cannot handle something that I do occasionally (Macs are expensive for what you get). That's why I recommend(ed) the G5 + existing monitor. If it can handle everything you do, then okay, but if it can't handle something that you may do occasionally, then go with the better machine if it's going to be a pain.
The eMac suggestion was a good one. It's cheaper than an iMac, with better specs (except for the screen). But the iMac is a good choice for iTunes and Office work you may do.