I have an Intel D945PVS motherboard with the Sigmatel 9223 chipset. My research tells me that it's next to impossible to get that thing working in Leopard. For simplicity's sake, it would be worth it to invest in a USB soundcard, as I hear many of them work with OSX86.

I own a guitarport (USB&Line-In based guitar input), so I would really like to have a card with Line In, but I haven't seen anything regarding Line In in the 10.5.2 HCL. Is this possible?

I would be willing to spend up to $50 or so for a good card. If 5.1 and/or line in are possible, I would probably be willing to spend more than that. What do you recommend?

EDIT: I found this card on Newegg for under $20, with 5.1 and Line In. Does anyone know if this card will work, or can someone recommend something similar that has been tested? Thanks

In essence your GuitarPort function as a USB audio interface. Prior to getting my RME HDSP I was using my POD XT connected via USB to record and monitor (turns up as an USB audio interface in OSX when you install the drivers). No 5.1 though. I don't know about that USB interface you linked to. Might work. It's pretty cheap so why not. Looks like it has mini-tele connectors so you may have to get RCA -> mini-tele cables to connect your GuitarPort.