I just can't leave it at this. lol PCI isn't just the slots on your motherboard, it's the entire bus that all the components, whether connected with in a slot or on the bus, are connected to the processor through. Here's what I get with lspci (run as root to see the stuff on the PCI bus).
Code:
lspci
00:00.0 Host bridge: nVidia Corporation nForce2 AGP (different version?) (rev c1 )
00:00.1 RAM memory: nVidia Corporation nForce2 Memory Controller 1 (rev c1)
00:00.2 RAM memory: nVidia Corporation nForce2 Memory Controller 4 (rev c1)
00:00.3 RAM memory: nVidia Corporation nForce2 Memory Controller 3 (rev c1)
00:00.4 RAM memory: nVidia Corporation nForce2 Memory Controller 2 (rev c1)
00:00.5 RAM memory: nVidia Corporation nForce2 Memory Controller 5 (rev c1)
00:01.0 ISA bridge: nVidia Corporation nForce2 ISA Bridge (rev a4)
00:01.1 SMBus: nVidia Corporation nForce2 SMBus (MCP) (rev a2)
00:02.0 USB Controller: nVidia Corporation nForce2 USB Controller (rev a4)
00:02.1 USB Controller: nVidia Corporation nForce2 USB Controller (rev a4)
00:02.2 USB Controller: nVidia Corporation nForce2 USB Controller (rev a4)
00:04.0 Ethernet controller: nVidia Corporation nForce2 Ethernet Controller (rev a1)
00:08.0 PCI bridge: nVidia Corporation nForce2 External PCI Bridge (rev a3)
00:09.0 IDE interface: nVidia Corporation nForce2 IDE (rev a2)
00:0d.0 FireWire (IEEE 1394): nVidia Corporation nForce2 FireWire (IEEE 1394) Co ntroller (rev a3)
00:1e.0 PCI bridge: nVidia Corporation nForce2 AGP (rev c1)
01:07.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 07)
01:07.1 Input device controller: Creative Labs SB Live! MIDI/Game Port (rev 07)
01:09.0 Ethernet controller: Atheros Communications, Inc. AR5212 802.11abg NIC ( rev 01)
01:0b.0 RAID bus controller: Promise Technology, Inc. PDC20376 (rev 02)
03:00.0 VGA compatible controller: nVidia Corporation NV20 [GeForce3 Ti 200] (re v a3)
As you can see, even the AGP runs on the PCI bus. I used to wonder the same thing that you do about the PCI stuff. lol