this is what I got from the intel website. I copied it from the specification section of Mobile intel 945 GM Express Chipset(the one I have in my notebook). This shows that it is possible to add a separate graphic card. But adding the card will void the waranty i guess. I will try the asus technical help to see if they do this kind of stuff(changing the graphic card for the customers)
Discrete Graphics using PCI Express*
• One 16-lane (x16) PCI Express port for external PCI Express-based graphics card.
• Compliant to the current PCI Express* Base Specification base PCI Express
frequency of 2.5 GHz only.
• Raw bit-rate on the data pins of 2.5 Gb/s, resulting in a real bandwidth per pair of
250 MB/s given the 8/10 encoding used to transmit data across this interface.
• Maximum theoretical realized bandwidth on interface of 4 GB/s in each direction
simultaneously, for an aggregate of 8 GB/s when x16.
• 100-MHz differential reference clock (shared by PCI Express Gfx and DMI)
• STP-AGP/AGP_BUSY Protocol equivalent for PCI Express-based attach is via creditbased
PCI Express mechanism.
• PCI Express power management support
• L0s, L1, L2/L3 Ready, L3
• Hierarchical PCI-compliant configuration mechanism for downstream devices (i.e.,
conventional PCI 2.3 configuration space as a PCI-to-PCI bridge).
• PCI Express Extended Configuration Space. The first 256 bytes of configuration
space aliases directly to the PCI compatibility configuration space. The remaining
portion of the fixed 4-KB block of memory-mapped space above that (starting at
100h) is known as extended configuration space.
• PCI Express Enhanced Addressing Mechanism. Accessing the device configuration
space in a flat memory mapped fashion.
• Automatic discovery, negotiation, and training of link out of reset
• Supports traditional PCI style traffic (asynchronous snooped, PCI ordering)
• Supports traditional AGP style traffic (asynchronous non-snooped, PCI-X Relaxed
ordering)
• Support for peer segment destination write traffic (no peer-to-peer read traffic) in
Virtual Channel 0 only.
• APIC and MSI interrupt messaging support. Will send Intel-defined “End Of
Interrupt†broadcast message when initiated by the CPU.
• Downstream Lock Cycles (including Split Locks)
• Automatic clock extraction and phase correction at the receiver.