just wanted to get opinions. I downloaded the whited00r ios for iphone 3G, and its based on 4.3.2. itunes shows the phone as having 4.3.2, as does the phone. its pretty, haha, but maddeningly slow. regular rdsn0w doesnt work for me because I have a Powermac G5, and redsn0w is intel only. i cooked a custom 4.2.1 firmware with pwnage tool, but itunes kept giving a 1600 error.

is there a way to speed up this firmware, or is it better to just downgrade?

In my experience, iOS 4.2.1 was the most recent that ran reliably at all on the iPhone 3G. You can get a 1600 error either because of a faulty cable, bad USB hub or port, or because you're attempting to restore a custom firmware to a device in recovery mode and not DFU. It's most probably the DFU issue -- make sure the phone is in DFU mode when you attempt the shift-restore, or it will fail. If that still doesn't work, use iReb to kick the phone into DFU. You should be able to successfully restore 4.2.1 to the phone at that point.