Rock solid and as fast as a greased snake
Now that is what Vista should be, with very new hardware it runs OK, but code bloat and extra features have caused it to chug a bit. Strange when those extra feature are promoted as a reason to buy it.
Now Apple have announced that the next version of OS X is going to focus on speed, small foot print and reliability maybe Microsoft will copy them, and sort out Vista, after all it is only the OS it should only really be running your programs, do that nice and fast and make sure it doesn't crash and they will have happy customers. Microsoft have seemed to forget that.
I blame Balmer, then again I blame him when it rains.