Comment Re:only for nerds (Score 1) 66
In theory, the answer is a qualified "maybe". Most new laptop discrete video cards connect via mini-PCIe, and I believe there's some anecdotal degree of physical compatibility between Alienware/Dell and someone else (Clevo, I think). As a practical matter, if you you're talking about buying a better video card on eBay that was explicitly designed for your exact model (say, upgrading from the cheapest ATI card to the best Quadro), you'll probably be OK. Everything else is a crapshoot.
Apparently, screw holes are a big, big problem with cross-device compatibility... different laptops put them in different places, even when the electrical interface, shape, thickness, and cooling arrangements are compatible.
There are actually a lot of relatively upgradable laptops out there (as long as you don't insist on one that's a glued/laminated-together 1mm-thick Apple-inspired abomination that's built like a cell phone). The problem is, it's nearly impossible to make any kind of informed purchase decision in advance of actually buying anything. The information you need just plain isn't reliably available until some brave soul tries doing it, takes pics, measures things, and posts the pics to his blog. Thinkpads are somewhat of an exception... but Lenovo made a new mess of their own (and got lots & lots of hate) when they started whitelisting specific mPCIe cards in the EFI BIOS and refusing to enable cards not on the list.
Put another way, there's a lot that can go wrong, and you're at least as likely to burn cash on parts with limited resale value that won't ultimately work, and can often be purchased only used on eBay from sellers who harvested them from broken laptops bought for scrap.