Comp Upgrade Help

I want to do an upgrade on my computer as it’s getting old but I am not ready to drop Big $ nor do I want to upgrade my video card and ram as of now. My current setup is an nvidia epox EP_8rda3+ and and AMD Athalon XP 1.10 GHz. I need some recommendations on a motherboard and processor that uses agp slots, supports SATA hard drives and has a sPDIF input preferably. I haven’t really been keeping up with whats good and not so recommendations would be helpful.