Hi got a Sony Vaio RX 404 with a Geforce 4mx 460 graphics card in it. Thinking of changing it for something else as find games often seem to freeze up on occassoins. Already added ram to 512.
So do i need more ram or a getter graphics card?

well you probably can upgrade it, but not much. here is the reason:

your computer is probably locking up because of overheating the graphics card. I had a similar sony (rz32g) fand it had the mx 440 in it. It had a passive cooler (no fan) and it would over heat as well. Your case is so small that the cooling in it is next to nothing. If you could, i would recomend buying a new case to stick your parts in. Here is another reason why i suggest a new case. The power supply inside of your case is probalby not much. my guess is 250-295 watts. (you should verify this and post this back if you can. You can find it out by looking at the sticker on the side of the powersupply if you pull the side case pannel off.) With a new graphics card you will need more power than that. A min of 350 but i recomend 420 min. You could try and buy a new powersupply and fit it into your case but it wont fit. YOur case is super small form factor and no normal psu's will fit in there. (I ran into this same problem).

So, if you want a new graphics card, you will need a new case and powersupply as well.

Hope this helps