Hmmm, for me (on my PC's)
Nic- Intel Pro 100's GREAT Nic, low CPU Usage (less than %2 at full load) NEVER a problem in EVERY chipset I've ever tried it in!
Nic for a PCI Mac- D-Link 530TX (regular old PC version) works fine, even with the onboard Ethernet Extensions and is CHEAP!
Keyboard - I'm using just a generic HMB (Acer) It's the Smallest 101-Key Natural Keyboard on the market (need valuable desk space)
Mouse - I LOVE the Intellimouse Explorer, but be warned I've RMA'd 3 in the last year and a 1/2. I hate my Logitec Mouseman Optical, but it's been working perfectly for 2 1/2 years.
Speakers - I dunno, never bought a set of PC Speakers. I use an old Mitsubishi 400watt Amplifier w/ a set of old JBL Control 5's.
Webcam - Couldn't tell you either, Mine was free, it's an IBM PC-Cam, it works fine!