I've got to be either a computer professional or I'm blessed by Bill Gates personally. I have vista and I have 2GB RAM, and I didn't have to remove any of it. Search google for "memtest", download it and let it run for a long time, my guess is it will come up with a lot of faults in either or both of your RAM sticks. I'm updating Vista quite often, I have set it to notify me of new updates and i always download them, there hasn't been a problem once.
However just today I learned/heard that it can produce some weird bugs, try downloading the updates again and see whether that results in the same errors, though backup any important data before doing so.

Apart from that it could still be a hardware problem and it always reminds me how often I had Linux crash. XP doesn't always work properly either btw, the world isn't perfect and Vista is new. Yeah, I got it for free.

Oh, I need a point, well, I don't think it's a joke, it's not perfect, but joke is too strong a word.