Xorg works right away only on some select distros or the kernel compiled from source with proper settings (i assume), as the i915 driver doesn't do anything. It supports 16-bit color in vesa mode only with no acceleration.

lspci -vvnnk

00:02.0 VGA compatible controller [0300]: Intel Corporation 82815 Chipset Graphics Controller (CGC) [8086:1132] (rev 02) (prog-if 00 [VGA controller])
	Subsystem: Hewlett-Packard Company 82815 Chipset Graphics Controller (CGC) [103c:1245]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 10
	Region 0: Memory at f0000000 (32-bit, prefetchable) [size=64M]
	Region 1: Memory at ec000000 (32-bit, non-prefetchable) [size=512K]
	Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
	Capabilities: [dc] Power Management version 2
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-

hwinfo

18: PCI 02.0: 0300 VGA compatible controller (VGA)
  [Created at pci.386]
  Unique ID: _Znp.DEO8Dmi3AN5
  SysFS ID: /devices/pci0000:00/0000:00:02.0
  SysFS BusID: 0000:00:02.0
  Hardware Class: graphics card
  Model: "Intel I815"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x1132 "I815"
  SubVendor: pci 0x103c "Hewlett-Packard Company"
  SubDevice: pci 0x1245 
  Revision: 0x02
  Memory Range: 0xf0000000-0xf3ffffff (ro,non-prefetchable)
  Memory Range: 0xec000000-0xec07ffff (rw,non-prefetchable)
  Memory Range: 0x000c0000-0x000dffff (rw,non-prefetchable,disabled)
  IRQ: 10 (no events)
  I/O Ports: 0x3c0-0x3df (rw)
  Module Alias: "pci:v00008086d00001132sv0000103Csd00001245bc03sc00i00"
  Driver Info #0:
    XFree86 v4 Server Module: intel
    Color Depths: 8, 16, 24
    Extensions: 
    Options: 
  Driver Info #1:
    XFree86 v4 Server Module: intel
    3D Support: yes
    Color Depths: 16
    Extensions: dri
    Options: 
  Config Status: cfg=new, avail=yes, need=no, active=unknown