Are most laptops video upgradable? And is it very difficult?
Also, what would be a decent low expense dedicated memory video card for a laptop for video and gaming until I can afford to upgrade to a 7800?
The majority are not. Dell had an upgradable series a while back, but few took advantage of it and ultimately Dell stopped marketing them as being upgradable.
In short, get the video capabilities you want when you buy the laptop.