does it matter in which order you install ram i have 512 and 1 gig, does it mtter which goes in which slot?

For some motherboards yes (the biggest must be in the first slot,) for others no. Just to be safe, put the 1 gig in slot number 1 (it should say on the motherboard) and the 512 in slot 3 if you have 4 slots or slot 2 if you only have 2 slots. For motherboards with 4 slots, slot 1 and 3 are the fastest.

Note: If this doesn't work don't dismay, your computer will not boot up, but nothing permanently bad will happen. You'll just have to switch the memory around (try all the different combinations.)

As stated previously some yes some no. One one point though I must point out that the memory slots are numbered starting with zero(0) instead of 1(one). Ideally I would put the higher memory in slot 0 and the other in slot 1

ideally the slot closest to the memory controller should have the 1GB RAM and then the next slot should have 512 RAM

nope

Wouldn't think so.