If your running Vista 32bit then it won't recognise 4GB of RAM. You need to run the 64bit version to utilise that amount. Thats why I only use 3GB as I only have the 32bit version. I've never heard about graphic cards affecting memory amount altho' they can effect the swapfile size . As long as your not getting lock ups all the time I shouldn't worry. Like I said in my previous post I do get a lock up now and again and like you there is no pattern. One thing I have noticed is Vista is always a little twitchy after some sort of change. This could be new drivers or hardware and it always seems to take a while to settle back down.

You say your graphic card is a GTS or something, Its probably a geforce 8800 GTS either 640MB or 320MB.

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