The USB to Serial adapters do work, but there are compatibility issues with each specific device.
You still need support (driver or built-in to OSX); for example an Epson 600 printer won't work in OSX because there's no driver support. So, check with the vendor or on webboards to make sure the item you need to enable works with a serial adapter.
Mostly they're used by musicians who want MIDI support (which is a serial protocol).
OSX has no built-in serial support.
In general they work fine in OS9 assuming you have a product that worked with a Mac with real serial ports & OS9.
As for the cellphone lock codes and/or vendor lock codes, you're probably better off borrowing a PC. If it's a legitmate phone (ie the contract that paid for the phone has ended) you can sometimes get the original wireless provider to agree to allow it to be changed; take it to their dealer after getting the go-ahead.
Don't hold your breath, however; I couldn't get Rogers to unlock a paid-contract phone even though I wanted to use them as a provider.
I suggest the PC simply because it's a difficult, sometimes impossible, process at the best of times; you will find it easier to get it up if you eliminate at least one possible source of failure (ie an incompatibility with a Mac and/or VPC). Good luck.
[ November 21, 2003, 01:04 PM: Message edited by: gordguide ]