Here's a bit of an advertising 'ha-ha' for you. It appears that Crucial's suggesting you buy more RAM because Vista likes to use it all up.
While its true that half the time these days, programmers don't seem to care about memory efficiency, is Vista really that bad? Some reckon it's 'bloated', while others say that the final release is actually rather good; it'll use a lot of memory for caching, but only if it's not needed for other stuff.
Crucial's stance is, and we quote: "Vista is memory-hungry". Look, it's right here, in an advertising campaign they're running online:

Do we live in a world where hardware is upgraded to meet software requirements, rather than software written to work well on existing hardware? The jury's still out on that, we reckon, and it probably will be for evermore, but Crucial seems fairly sure that if everyone bought more of its RAM, Vista and its users would be happier.