Audio Recording on a Quicksilver G4?

I have an old Quicksilver G4 that I want to use for recording (Guitar / microphone – using mic to record infront of guitar amp). The computer doesn't have mic-in or line-in at the back.
I'm wondering if there are USB / firewire audio interfaces / sound cards or something similar that can record with low latency into either Garage Band or ProTools, etc.

A quick search on eBay found this: Griffin iMic2

http://cgi.ebay.com.au/Griffin-iMic...ryZ25446QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

This crappy Hong Kong one – would that work fine?:

http://cgi.ebay.com.au/USB-6-Channe...oryZ3701QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

What about this? http://www.core-sound.com/audiophile_usb/audiophile_usb.jpg

http://cgi.ebay.com.au/ws/eBayISAPI...m=270272011411&ssPageName=STRK:MEWA:IT&ih=017

It'll probably go for loads more than my budget though. I'll keep an eye out.

Does anyone know if these are any good for my purposes? Perhaps I'd be better to find an old PCI sound input device – does anyone know of any semi-professional cards would be good for my uses, that would work fine in the G4?

I'll set a budget at $40 – 60 AUD. The cheaper, the better though. Second hand is fine (and preffered if it's cheaper).

Thanks!

Well, I'm pretty much a student that wants to get his songs down. Before, I was either recording electric (with a Windows XP) with guitar > pedal (acting as pre-amp) > line in (then Kristal using Amplitube), and that was fine latency-wise using Asio4All. For acoustic stuff, I used a mic > stereo amp > tape out > line in, and that was pretty good quality – good enough for my purposes.

I don't really want anything much better quality than that, and I don't need to be able to use Guitar Rig 3, as my amp is more than versatile enough, and I find it way to digital.

The only reason I'm looking for one of these is because the Mac doesn't have Line-in.

I'd love to be able to stretch my budget further, and I know it's an investment, but at the moment I'm tight on cash, but I need some way to record with this Mac.

Thanks for the advice so far!