Preferably something that doesnt produce too much heat not exacly in the best case on the planet, and also something cheap as chips.
Can I run a second card in a PCI-e 1x slot?
The short answer is yes, the long answer is it's a bit more complicated. Firstly, you normally have to remove the end of the x1 slot to physically fit a graphics card in, although there are a couple of x1 graphics cards floating around - these are usually very slow cards anyway, and not worth folding on. Details on how to remove the end of the slot
here.
Secondly, a PCI-e x1 slot only provides 25W power, unlike a x16 slot which provides 75W. This means you have to be using a card which draws <25W (unlikely) or <100W with a 6-pin adaptor (or <175W with two 6-pin adapters, etc). However, not all cards will follow this principle, presumably because they require more than 25W from the PCI-e slot for whatever reason. The safest way is to buy a card you either know will work in a x1 slot, or one that you're happy running in a x16 slot/can easily sell with minimal hassle if it won't work in a x1 slot.
The 8600GTS I have is apparently meant to draw 75W, but doesn't have a 6-pin power connector, so wouldn't work in a x1 slot. The 9600GT I have is meant to draw 95W and has a 6-pin power connector so
may work in a x1 slot, but I haven't tried it so don't know for sure.
According to the 'bay they're going for £40+ inc postage, I could knock a tenner off that if you're interested?