Just gonna go ahead and say it:
Bad idea. For SOOO many reasons.
1) that only supports PCIe x1 speed, the cards you are looking at are all PCIe x16.
2) even if it works, you will only be able to use thaw power of the card on an external monitor.
3) there are all sorts of power issues here, even if you use an external PSU to power the cards 6 and 8 pin connectors, it will not be balanced right from what the card tries to draw from the PCIe slot. You will very likely kill the card, the adapter, or your laptop's expresscard slot.
4) you will probably kill any PSU you try to use after a few months as well due to imbalanced loading. They are designed to power a full system, not a single card (which would ONLY draw from the 12v rail).
5) you WILL have driver issues. Games and windows will not like switching between those setups.
Do yourself a favor and save up and build a desktop. Do not try to Frankenstein desktop parts into laptops, it will not work out for the best.Edited by kevingreenbmx - 3/30/11 at 5:12pm