@ Seero, this isn't actually very complicated. I have already tried it is as a proof of concept with a 9800 GT from another computer, and it worked fine. It was literally plug and play. I simply need to put my computer to sleep, plug it in, and then resume the computer. The external display was powered by the external GPU, and the internal display was powered by the Intel HD chip. This was done with Windows 7 and I only had to pay for a ~$90 part.
Now, to explain my current solution:
As I mentioned earlier, I'm utilizing the
expresscard slot not a PC card slot. Expresscard is essentially a PCIe x1 slot due to its direct connection to the system bus over a PCI Express ×1 lane. This is the reason why everything works plug and play. To Windows, this is no different then a desktop video card. It cannot differentiate between the link speeds, or rather, doesn't care. Drivers start installing automatically, and games figure out what to do from there.
With regards to the power supply, I need to power the card, therefore I need to use an external PSU. All cards need a PSU, because the laptop doesn't provide power over the slot. Furthermore, expresscard doesn't even have that capability (and neither does my laptop's PSU).
About link speed:
Okay, here is where things get tricky. I am currently connect by x1, which means I get roughly 50% of the performance that I would get connected via a standard x8 or x16 desktop mobo (no cards really need the extra bandwidth provided by x16 yet). This scaling is irregardless of the card. However, as with any PC connected device, there are diminishing returns.
PCIe 2.0 x1 will likely never happen on laptops due to USB 3.0. Expresscard 2.0 was slated to come out late 2010, but was overshadowed by USB.
Now, I can increase my performance by using tweaked drivers and making tweaks of my own like disabling hypermemory and HDMI sound (about 15% better). So I personally get 65% of the performance of a desktop card. I wish there was a way to utilize the Lenovo dock connector at the bottom of my computer, but there isn't.
Some people have done even better by using their wifi's mPCIe slot to get an x2 link. That would provide nearly 90% of the performance after tweaks.
It would be interesting to see what can be done with the Intel Thunderport technology when that gets rolled out in PCs, since the data can simultaneously travel both ways.
I need to use an Nvidia card because the Nvidia Optimus driver allows you to clone to your internal LCD if you have an Intel 4500MHD/HD chip when using a Nvidia 4xx or 5xx card. Then means that I could use the internal display for a LAN party situation.
Hope I cleared some things up.
@happy_medium:
I have the i7 640L. If I remember correctly, it runs at 2.0, and can turbo up higher. It's also a ULV proc. I know that this will not be the bottleneck for sure.
I'm sure that games will run even nicer on the x220 (or whatever it will be called) with Sandy Bridge.
Other specs that matter for gaming: 8GB RAM (total overkill, but got a deal) and 750 GB HDD (I need the space).
A side note: That RAM is amazing. Once Windows loads up the standby memory, I can open all my most used applications as quickly as I would with an SSD. Windows 7 does some amazing stuff with a lot of RAM.
I also think that Lenovo does something proprietary to Windows, because a loaded install loads quicker on my laptop than a fresh install on a significantly faster laptop. My drive also runs @ 5,200 RPM, though it is an adv. sector drive.