Probability of both graphics cards with probs within a short period?

Ah, in that case it's like that because that seemed to be the only combination that actually worked.

I've got 3 sticks of RAM altogether: two 1GB sticks, and one 2GB stick - the two 1GB sticks are in the first 2 slots, and the 2GB stick is in the first of the 2nd 2 slots (if that makes sense?)

So [1GB-1GB/2GB-*empty slot*] - I *think* (might need double-checking, but I'm 80% sure it's like that)

a code 43 indicates a device has failed, but it does not mean the device has actually failed, sometimes it may well mean just that but not always, more often than not it's the device drivers getting all messed up.

microsoft do have a fix for it as it is a known issue that can occur.
not a quick fix if your wondering as there isn't one.

it may be more effective if you remove the problem device before proceeding.

step 1-uninstall the device drivers completely, use a driver sweeper to remove any remnants delete any folders or added apps that were also installed. (this bit must be done with no shortcuts failing to remove any remaining remnants will mean wasting time on the following steps.
step 2-run a check disk, there is a reason for it.
step 3-reinstall the device drivers and it should be working.

if it doesn't work after that then the graphics card is most likely done.