'Its incredibly slow because Vista attempts to cache everything in memory, but then doesn't have enough memory to handle program launches.'
Using left over memory to cache things is what you should do. Linux does it too, I would assume OS X does.
You periodically flush any changed bits in the cache to disk.
* When programs try and use more memory, you simply throw away the cache (except any changed bits you haven't yet written to disk).
* When they don't, your file access is 300,000 times faster
I think the key words in your sentence is "left over".
Vista with 1GB does not really have "left over". Either that, or the Vista's "pre-emptive app caching" algorithms are really terrible, because the first two apps my girlfriend always launches are 1) iTunes and 2) Firefox. It should figure that out and launch them quickly, instead of disk thrashing for 15-30 seconds and then launching them.
Using left over memory to cache things is what you should do. Linux does it too, I would assume OS X does.
You periodically flush any changed bits in the cache to disk.
* When programs try and use more memory, you simply throw away the cache (except any changed bits you haven't yet written to disk). * When they don't, your file access is 300,000 times faster