Uhh... More Rams it is then. My dad has another 2GB RAM chip in his laptop. I'll take it out later and put it it mine, see how things go with it. Vista is only 32bit though, not sure how much I'll gain from that.
You'll get the whole 4Gb, pretty much, though Vista will only report 3.5Gb. Windows moves stuff up into high RAM (pointers to video memory, stuff like that) that uses up a chunk of memory. With 4GB, it moves that stuff into the top .5 that you can't use anyway, leaving pretty much all of the lower 3.5 available. Even with all my drivers, antivirus, etc loaded, cacheman reports around 3.1Gb available (under XP -- YMMV).