Sobering said:
I'm sorry to say but there is no such thing as getting it right the first time around.
Yes, there is. Instead of buying the last of an old chip architecture, buy the first of the new
Which is exactly what the current iMac has: 64-bit Core 2 Duo.
That in turn will keep evolving and improving (Santa Rosa, higher Ghz, etc. etc.), which is what computers always do. But at this moment the chip architecture in Macs has crested an important wave, and that makes it a good time to buy.
I always tell people to wait IF they don't really need something yet. But if you need something, now isn't a bad time. Leopard won't cost much, as people have said.
You could wait for January to get iLife 07 (probably), but I make do skipping every other iLife version. The OS is a more important upgrade for me, and that's many months away.