I for one have been really impressed with the stability of Windows Vista, even though this only the first beta.
Instead of installing Vista in Virtual PC or something, I opted to wipe
out an XP installation and test it that way. The machine I installed it
on has an Athlon XP 2800+ and 512 MB of RAM, so it's pretty speedy.
Under XP, I never really had any problems except for one device driver
issue. If I left the computer running for an extended period of time,
it would completely freeze up so that the next time I went to use it,
I'd have to hard reset the damn thing. Of course, after XP restarted it
would detect that a major error had occurred, and would let me send an
error report, which I always did. It never could tell me what the
problem was though, and it certainly couldn't prevent the issue from
bringing down the entire computer.
Under Vista Beta 1, if I leave the machine running for an extended
period of time, it never freezes up! Once or twice I have come back,
pressed a key to wake up the computer, and found that Vista had
encountered an error, but the machine never stopped working. A little
message box saying an error had occurred is all that I see, and so I
send off the error report.
Now while in this example Vista seems to be much more stable (device
driver doesn't bring down the entire system), it would be really nice
to know what caused the problem! Windows XP doesn't tell me that
information, and in it's current incarnation, neither does Vista
unfortunately. Something we'll see in the future, hopefully?