Hey, Thanks for the replies!
Well, the 'good stick' I have in now has only been tried in the second slot, whereas my other RAM stick, which in slot 1 failed to boot up at all, and in slot 2 worked for a while, but froze on shutdown. I'm a bit hesitant to put this stick in the what I think is the 'bad' slot in case of the event that it somehow messes up my good stick.
I did have a little go with booting up a game with this good stick in (with the lowest specs due to only have 2GB ram now) just to test It and it did still freeze...so I'm not sure if it has caused electrical damage to something else on my computer...device manager and all that jazz says that everything is working correctly, but I never think I should trust it :/
It won't ruin the good stick unless the bad slot would actually be shorting the chips out; but you could tell this by seeing burn marks or some physical evidence on the bad stick.
If you're worried your good stick is going back, run a Memtest86+ ( Memtest86+ - Advanced Memory Diagnostic Tool ) on it, like I previously suggested. Firstly though, I would try putting the good stick in the other slot just to see if its a slot or a memory problem.
Edit: Also, a link to RAM that would workfor your laptop if you decide to order a new kit of two 2GB sticks: http://www.newegg.com/Product/Product.aspx?Item=N82E16820231156