Vista itself won't require a new or bigger power supply but if you want
to use the fancy Vista graphic features (Aero) you need a reasonably new
and powerful graphics card, that new card may require quite a bit more
power than your old card and as such you may be required to upgrade the
power supply unit so that it can adequately supply the power that the
new card needs.  That is not an uncommon issue when adding new, powerful
graphics cards to older computers.

John

Upgrading a VAIO, especially at best buy, is likely not cost efficient.

http://www.freecomputerconsultant.com/buying-guide.html

www.FreeComputerConsultant.com

Ugh! Probably one of the worst places to take a computer. The people who
work there (or at any of the big chain stores) are usually hired because of
their willingness to accept something close to minimum wage, not because of
their technical proficiency. If they knew anything, they could almost
certainly get a better job.

Why? How does he know that?

No!

Operating system don't require particular levels of power supplies. It's
hardware that does.

That's because there's nothing to find.

It's possible, but probably unlikely, that if the current power supply is
minimal, installing a different power supply might stress it beyond its
maximum output, but I wouldn't be so quick to believe the salesman. How many
watts is the current power supply? What is the configuration of the
machine--what CPU, how much RAM, what drives, etc.?

There is no "best." There are many good ones.

Hardware requires specific level of amperage per individual voltage leg from
the power supply.  These are additive per each piece of hardware in your PC
(Personal Computer).  Has NOTHING to do with Vista.

Vista requires a minimum level video card.  The video card requires a
minimum level of amperage per voltage leg from the power supply.  This is in
no way infers Vista requires a minimum level power supply.

Save your money/time.  Get a PC with Vista already on it.  And, of course,
has the hardware for playing with your pictures and music.

I have a Sony VAIO 1.8Ghz P4 system that I bought 2 years ago, and it does
have a non-standard Power Supply.

Most of these big box units that have non-standard anything have just
enough power supply to power what was/is included in the box and little
more.

Many newer video cards require MORE power than the cheap older ones, but,
not all. I was using a different video card in mine without problems, but,
when I added a second hard drive it was too much and there were some
intermittent failures.

I ended up purchasing a 480W PSU and then took the old PSU out, cut the
mounting bracket using my dremmel tool, installed the new PSU in the
bracket and then fit everything back into the case - it was very tight
fit, but it worked. (Key thing is to ensure that you don't get any metal
shavings inside the computer).

Vista doesn't know anything about power, it only knows that you are
installing it, so, it doesn't require POWER, but, it does require a LOT of
resources. Get at least 1.5GB RAM, get a 256MB to 512MB video card.