I haven't tried SP1 yet on my (64-bit) home machine yet, since it is plain foolish to consider the thing finished until it hits Windows Update. RTM means nothing until MS has decided it's good enough to roll out to every Vista machine.

So a lot of what I know about SP1 is still speculation. But over at Anandtech's first look one interesting new aspect of the service pack is mentioned.

If you have 32-Bit Vista, and 4GB of memory (or more) Windows will only report a small portion of your total RAM. It is in effect the total amount of address space you have remaining, which is roughly 4GB minus the space used by your video hardware.

Now in SP1, the issue is supposedly 'fixed', it reports the correct amount of RAM. It does not use it however. In fact (once again according to certain tests) it does not change anything bar the reporting. So your memory beyond 4GB is still useless, unless you use 64-Bit. You just dont know about it.

It means less complaints of course. Why did they persist with 32-Bit in the first place?